[Partial RFC] modesetting: support dri3 through glamor

This was really trivial, took me about an hour. I had some issues running Vulkan due to DRI3 issues(without MESA and using modesetting), that may have been because my distrubution didnt compile it for some reason though. This is only compile tested right now(on server 1.20), because I think there is something I missed here(as in DRI3 is supported in modesetting somewhere else I dont know about), hence the [Partial RFC].

changed the description

added 2 commits

• 9499fe38 - include/os: redefine strlcat only if we dont have it
• b034d913 - modesetting: support dri3 through glamor

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mentioned in merge request xorg/driver/xf86-video-nv!23

Do we even still need our string functions at all ?

@alanc @whot

strlcat & strlcpy? I suppose we could drop support for GNU libc versions older than 2.38, but that would probably eliminate most of the enterprise linux distros that are the ones left still packaging Xorg. Since glibc 2.38 just released a year ago, that seems a bit aggressive.