scons: loader: use libdrm when available

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/loader/SConscript

@@ -12,6 +12,10 @@ if env['udev']:
     env.PkgUseModules('UDEV')
     env.Append(CPPDEFINES = ['HAVE_LIBUDEV'])
 
+if env['drm']:
+    env.PkgUseModules('DRM')
+    env.Append(CPPDEFINES = ['HAVE_LIBDRM'])
+
 # parse Makefile.sources
 sources = env.ParseSourceList('Makefile.sources', 'LOADER_C_FILES')