weston-launch: Add sysmacros.h include for major()

Same as with c4d7f66c, but I hadn't done a full-tree rebuild so didn't
see this one go by.

Signed-off-by: Daniel Stone <daniels@collabora.com>
diff --git a/libweston/weston-launch.c b/libweston/weston-launch.c
index 140fde1..eecb911 100644
--- a/libweston/weston-launch.c
+++ b/libweston/weston-launch.c
@@ -42,6 +42,7 @@
 #include <sys/wait.h>
 #include <sys/socket.h>
 #include <sys/signalfd.h>
+#include <sys/sysmacros.h>
 #include <signal.h>
 #include <unistd.h>
 #include <fcntl.h>