meson: implement split-debug
What does this MR do and why?
Why ?
Mesa is a big project, and having the ability to use split debug symbols allows the project to distribute the debug files aside, for example for CI failures, get loaded on request.
How?
Add support into meson, so we can use it later for example in !20435 (closed)
meson: implement split-debug
split-debug uses C args `--gsplit-dwarf` and linker args `--gdb-index`
to achieve split debug, speed up the CI linking, and allow us to
distribute debug symbols standalone.
Signed-off-by: David Heidelberg <david.heidelberg@collabora.com>