test: simple-xinit: add _X_NORETURN

fix warning:

> ../test/simple-xinit.c:58:1: warning: function 'usage' could be declared with attribute 'noreturn' [-Wmissing-noreturn]

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1429>

test/meson.build

@@ -2,6 +2,7 @@ simple_xinit = executable(
     'simple-xinit',
     'simple-xinit.c',
     include_directories: inc,
+    dependencies: [ xproto_dep ],
 )
 
 piglit_env = environment()

test/simple-xinit.c

@@ -25,6 +25,8 @@
 #include <dix-config.h>
 #endif
 
+#include <X11/Xfuncproto.h>
+
 #include <errno.h>
 #include <signal.h>
 #include <stdbool.h>
@@ -53,7 +55,7 @@ kill_server(int server_pid)
     }
 }
 
-static void
+_X_NORETURN static void
 usage(int argc, char **argv)
 {
     fprintf(stderr, "%s <client command> -- <server command>\n", argv[0]);