xkb: simplify marshalling

The Xkb protocol is a complex beast, and so is it's current implementation. In order to clear the road for #1701 it needs to be untwisted, cleaned up and simplified.

Intentionally untwisting xkb in smaller, easily digestible steps, otherwise review would have become pretty hard.

Major points:

• simplifying call and data flow (eg. try not to pass around partially filled reply struct, instead the required values explicitl)
• reduce very short lived heap allocations by using stack (scoped fields) instead
• prefer struct initializers instead of piece-by-piece assignments
• split out cases where replies can also be contained in another one (xkbSend*(), ...)
• collect reply fragments in local buffers, so the complete reply can be written out at once.

Once this queue is merged, further simplifications become easy -- see #1701..

Also makes it easier for adding non-socket/stream based transports (binder, shmem, virtio, ...).

mentioned in task #1727

added 81 commits

• 298ab25f...c4481fc2 - 50 commits from branch xorg:master
• c4481fc2...62a92738 - 21 earlier commits
• 27c25126 - xkb: XkbSendNames(): move common code into a helper macro
• 79008c4e - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• ba749c69 - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 12cf3938 - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• 448307ca - xkb: split XkbSendMap()
• 490b1d5f - xkb: split XkbSendCompatMap()
• 6e1d6e39 - xkb: split XkbSendIndicatorMap()
• 7ae3aade - xkb: split XkbSendNames()
• 9836ac89 - xkb: split XkbSendGeometry()
• b1d38fb5 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

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added 19 commits

• b1d38fb5...2e6aa64e - 9 earlier commits
• 9b71d8c4 - xkb: XkbSendNames(): move common code into a helper macro
• aa3c6942 - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• e0761c27 - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 6be25c35 - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• f0b9d1e8 - xkb: split XkbSendMap()
• 8f202ad5 - xkb: split XkbSendCompatMap()
• 8d61f8d6 - xkb: split XkbSendIndicatorMap()
• 49b0fc61 - xkb: split XkbSendNames()
• 83c21832 - xkb: split XkbSendGeometry()
• 09d90c60 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

added 10 commits

• 354ed978 - xkb: XkbSendNames(): pass in struct as value instead of pointer
• c4198c4c - xkb: XkbSendNames(): move common code into a helper macro
• fe60ae7b - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• a9ff378e - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 6856580c - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• 393b0f91 - xkb: split XkbSendMap()
• 26ee97c1 - xkb: split XkbSendCompatMap()
• 30ff68aa - xkb: split XkbSendIndicatorMap()
• 60e87b8b - xkb: split XkbSendGeometry()
• e55041ac - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

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added 18 commits

• e55041ac...7d3abbaa - 8 earlier commits
• 7c6bc314 - xkb: let SendDeviceLedFBs() fill buffer instead of writing directly
• e3394c49 - xkb: XkbSendNames(): pass in struct as value instead of pointer
• 339b2c77 - xkb: XkbSendNames(): move common code into a helper macro
• e2b857d5 - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• 0443a6e9 - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 6aa968cf - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• 39893b35 - xkb: split XkbSendCompatMap()
• 0c1c3aa1 - xkb: split XkbSendIndicatorMap()
• e7ce4a29 - xkb: split XkbSendGeometry()
• fa4002ad - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

added 11 commits

• af173a0f - 1 earlier commit
• d9e8ed74 - xkb: let SendDeviceLedFBs() fill buffer instead of writing directly
• 69f8197e - xkb: XkbSendNames(): pass in struct as value instead of pointer
• 6fc0026b - xkb: XkbSendNames(): move common code into a helper macro
• 876744cd - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• 00f8b404 - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 2be16819 - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• d0bfa4ee - xkb: split XkbSendCompatMap()
• 22caadb6 - xkb: split XkbSendIndicatorMap()
• 0e54e4d0 - xkb: split XkbSendGeometry()
• eaadb2c6 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

added 7 commits

• 7e637b04 - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• 70a06162 - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 4ba2c7dc - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• 957b989e - xkb: split XkbSendCompatMap()
• 96eb6d44 - xkb: split XkbSendIndicatorMap()
• 8eb9d8c6 - xkb: split XkbSendGeometry()
• ed8462b1 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

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added 6 commits

• 09610a32 - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• b82e6795 - xkb: split XkbSendMap()
• 7a7b3102 - xkb: split XkbSendCompatMap()
• 72b1a7a1 - xkb: split XkbSendIndicatorMap()
• 08b83fdc - xkb: split XkbSendGeometry()
• a071384d - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

Okay friends, removed all the VLAs from the queue (dropped them from history).

resolved all threads

added 2 commits

• d52ce1b7 - xkb: split XkbSendGeometry()
• 70d56bf2 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

added 169 commits

• 70d56bf2...27a5c591 - 141 commits from branch xorg:master
• 27a5c591...ccc323d0 - 18 earlier commits
• 95c1a0f1 - xkb: XkbSendNames(): pass in struct as value instead of pointer
• 6851c9a0 - xkb: XkbSendNames(): move common code into a helper macro
• 18751685 - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• 42985c6c - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• 60bf7d20 - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• 2246c375 - xkb: split XkbSendMap()
• 05e49a61 - xkb: split XkbSendCompatMap()
• cff2da4e - xkb: split XkbSendIndicatorMap()
• 756e788e - xkb: split XkbSendGeometry()
• 7a105774 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

added 356 commits

• 7a105774...a0834009 - 328 commits from branch xorg:master
• a0834009...5d2679f4 - 18 earlier commits
• c2c09f15 - xkb: XkbSendNames(): pass in struct as value instead of pointer
• 66901951 - xkb: XkbSendNames(): move common code into a helper macro
• bfd2a84e - xkb: XkbSendGeometry(): pass in struct as value instead of pointer
• 8a216663 - xkb: ProcXkbGetKbdByName() simplify reply struct initialization
• bfd5ca19 - xkb: ProcXkbGetKbdByName(): static initialization of sub-reply structs
• 228fade0 - xkb: split XkbSendMap()
• 5f667c59 - xkb: split XkbSendCompatMap()
• dcefd215 - xkb: split XkbSendIndicatorMap()
• e75ac011 - xkb: split XkbSendGeometry()
• 4d134256 - xkb: ProcXkbGetKbdByName(): collect sub-replies in buffer and write at once

Compare with previous version

@p12tic