[PATCH weston] compositor: add missing help text

[JoonCheol Park]

The headless-backend.so was missing in available backend list

Signed-off-by: JoonCheol Park <jooncheol at gmail.com>
---
 src/compositor.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/compositor.c b/src/compositor.c
index 38c0775..0d4acda 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -5039,6 +5039,9 @@ usage(int error_code)
 #if defined(BUILD_RDP_COMPOSITOR)
 			"\t\t\t\trdp-backend.so\n"
 #endif
+#if defined(BUILD_HEADLESS_COMPOSITOR)
+			"\t\t\t\theadless-backend.so\n"
+#endif
 #if defined(BUILD_RPI_COMPOSITOR) && defined(HAVE_BCM_HOST)
 			"\t\t\t\trpi-backend.so\n"
 #endif
-- 
1.9.1