meson/xwayland: No libdrm nor epoxy without glamor

When building Xwayland with neither DRI nor GLamor support enabled with
the Meson build system, the resulting binary would still link against
libdrm and epoxy even though those are not used/needed.

Make sure we require and link against libdrm and epoxy only if needed.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
3 jobs for xwayland-build-libdrm in 8 minutes and 14 seconds (queued for 28 seconds)
Status Job ID Name Coverage
  Docker Image
passed #508463
debian-testing

00:00:38

 
  Build And Test
passed #508464
autotools-build-and-test

00:07:36

passed #508465
meson-build-and-test

00:02:17