Bump libdrm version requirement and remove unecessary ifdef's

There are some features that are available only if the user's libdrm version is not too old: format modifiers require at least libdrm 2.4.71, atomic API at least 2.4.78 and blob formats at least 2.4.83. Commit 1/2 bumps libdrm requirement to 2.4.83 (the oldest version that support these features). Major distributions already support libdrm 2.4.91, so it's safe to apply the commit. Here are some links that prove this:

• Debian Stable: 2.4.97 - https://tracker.debian.org/pkg/libdrm
• openSUSE Leap 15.1: 2.4.97 - https://software.opensuse.org/package/libdrm
• Ubuntu Xenial: 2.4.91 - https://packages.ubuntu.com/search?keywords=libdrm-dev
• Fedora 29 - 2.4.97 - https://apps.fedoraproject.org/packages/libdrm
• Arch Linux: 2.4.100 - https://www.archlinux.org/packages/extra/x86_64/libdrm/

Commit 2/2 removes #ifdef checks (for HAVE_DRM_ADDFB2_MODIFIERS, HAVE_DRM_ATOMIC and HAVE_DRM_FORMATS_BLOB) that are unnecessary for libdrm versions >= 2.4.83. Also, the checks to enable these flags are removed from libweston/backend-drm/meson.build. This makes the code cleaner and solves issue #250 (closed) ("Move #ifdef HAVE_DRM_ATOMIC code into new file").

added 1 commit

• d55ba66c - backend-drm: remove unecessary ifdef checks

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changed the description

added 9 commits

• d55ba66c...b544ac3a - 7 commits from branch wayland:master
• 28d26483 - build: bump libdrm requirement to newer version (2.4.83)
• ec6edc90 - backend-drm: remove unecessary ifdef checks

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mentioned in merge request !309 (closed)

added 6 commits

• ec6edc90...18462e89 - 4 commits from branch wayland:master
• 94e4068b - build: bump libdrm requirement to newer version (2.4.83)
• 6196b201 - backend-drm: remove unecessary ifdef checks

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enabled an automatic merge when the pipeline for 6196b201 succeeds

merged

Thanks a lot for your contribution! It looks good to me, so I've merged it now.

If you wanted to remove more unnecessary #ifdefs, the DRM_MODE_CONNECTOR_DSI and DRM_MODE_CONNECTOR_DPI checks have been unnecessary for a while now: those symbols are provided by libdrm and were introduced long before libdrm 2.4.68 (the previous lowest version we accepted), so those checks can just be removed now.

mentioned in merge request !312 (merged)

Daniel, thanks a lot for reviewing/accepting this MR!

I've opened a new one to remove the unnecessary #ifdefs you've mentioned

mentioned in merge request !317 (merged)

mentioned in commit pq/weston@1cb1604a

mentioned in merge request !496 (merged)

mentioned in commit pq/weston@9b94a7d8