egl_dri2: fix wayland_platform when drm_platform is not set

The build fails with implicit delaration of drmGetCap (xf86drm.h)
Were we're including the header only when building the DRM_PLATFORM.

Wayland backend can operate without DRM_PLATFORM so replace the
guard, and fold in drmGetCap() usage to silence compiler warnings.

Cc: Chad Versace <chad.versace@linux.intel.com>
Cc: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
1 file changed