meson: add git wrap for libdrm

Sometimes as a developer when a new version of libdrm is required, it's
nice to not have to install it somewhere and set up pkg-confing, and
just let Meson do it for us.

meson.build

@@ -1590,7 +1590,10 @@ foreach d : _libdrm_checks
   if d[1]
     set_variable(
       'dep_libdrm_' + d[0],
-      dependency('libdrm_' + d[0], version : '>=' + _drm_ver)
+      dependency(
+        'libdrm_' + d[0], version : '>=' + _drm_ver,
+        fallback : ['libdrm', 'ext_libdrm_' + d[0]]
+      )
     )
   endif
 endforeach
@@ -1599,7 +1602,8 @@ with_gallium_drisw_kms = false
 dep_libdrm = dependency(
   'libdrm', version : '>=' + _drm_ver,
   # GNU/Hurd includes egl_dri2, without drm.
-  required : (with_dri2 and host_machine.system() != 'gnu') or with_dri3
+  required : (with_dri2 and host_machine.system() != 'gnu') or with_dri3,
+  fallback : ['libdrm', 'ext_libdrm'],
 )
 if dep_libdrm.found()
   pre_args += '-DHAVE_LIBDRM'

subprojects/libdrm.wrap

+[wrap-git]
+directory=libdrm
+url=https://anongit.freedesktop.org/git/mesa/drm.git
+revision=main
+
+[provides]
+libdrm = ext_libdrm
+libdrm_amdgpu = ext_libdrm_amdgpu
+libdrm_etnaviv = ext_libdrm_etnaviv
+libdrm_exynos = ext_libdrm_exynos
+libdrm_freedreno = ext_libdrm_freedreno
+libdrm_intel = ext_libdrm_intel
+libdrm_libkms = ext_libdrm_libkms
+libdrm_nouveau = ext_libdrm_nouveau
+libdrm_omap = ext_libdrm_omap
+libdrm_radeon = ext_libdrm_radeon
+libdrm_tegra = ext_libdrm_tegra