compositor: add missing newline to help text

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/compositor.c b/src/compositor.c
index 5f9bbd1..3af7f93 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -4495,7 +4495,7 @@
 			"\t\t\t\tdrm-backend.so\n"
 #endif
 #if defined(BUILD_FBDEV_COMPOSITOR)
-			"\t\t\t\tfbdev-backend.so"
+			"\t\t\t\tfbdev-backend.so\n"
 #endif
 #if defined(BUILD_X11_COMPOSITOR)
 			"\t\t\t\tx11-backend.so\n"