libweston/launcher-weston-launch: Silence unused-function warning

libweston/launcher-weston-launch.c:58:1: warning: unused function
'is_drm_master' [-Wunused-function]
is_drm_master(int drm_fd)
^

Warning produced by Clang 3.8.

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>

libweston/launcher-weston-launch.c

@@ -55,15 +55,6 @@
 
 #include <xf86drm.h>
 
-static inline int
-is_drm_master(int drm_fd)
-{
-	drm_magic_t magic;
-
-	return drmGetMagic(drm_fd, &magic) == 0 &&
-		drmAuthMagic(drm_fd, magic) == 0;
-}
-
 #else
 
 static inline int
@@ -78,12 +69,6 @@ drmSetMaster(int drm_fd)
 	return 0;
 }
 
-static inline int
-is_drm_master(int drm_fd)
-{
-	return 0;
-}
-
 #endif