meson: install dri internal header

Reported-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

include/meson.build

@@ -66,3 +66,7 @@ if with_egl
     subdir : 'EGL',
   )
 endif
+
+if with_dri
+  install_headers('GL/internal/dri_interface.h', subdir : 'GL/internal')
+endif