meson: fix compositor build with xwayland disabled

If xwayland is disabled, compositor/weston is built without
compositor/xwayland.c, which defines wet_load_xwayland.

  compositor/fb12c4d@@weston@exe/main.c.o: In function `main':
  ../weston-5.0.0-169-g2d4cc4f4dd6a/compositor/main.c:3103: undefined reference to `wet_load_xwayland'

Provide an empty stub for wet_load_xwayland if xwayland is disabled.
With that we also have to remove xwayland.c from the autotools build
if xwayland is disabled, to avoid a multiple definition error.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Makefile.am

@@ -210,8 +210,11 @@ weston_LDADD = libshared.la libweston-@LIBWESTON_MAJOR@.la \
 weston_SOURCES = 					\
 	compositor/main.c				\
 	compositor/weston-screenshooter.c		\
-	compositor/text-backend.c			\
+	compositor/text-backend.c
+if ENABLE_XWAYLAND
+weston_SOURCES += 					\
 	compositor/xwayland.c
+endif
 
 # Track this dependency explicitly instead of using BUILT_SOURCES.  We
 # add BUILT_SOURCES to CLEANFILES, but we want to keep git-version.h

compositor/main.c

@@ -646,7 +646,9 @@ usage(int error_code)
 		"  --shell=MODULE\tShell module, defaults to desktop-shell.so\n"
 		"  -S, --socket=NAME\tName of socket to listen on\n"
 		"  -i, --idle-time=SECS\tIdle time in seconds\n"
+#if defined(BUILD_XWAYLAND)
 		"  --xwayland\t\tLoad the xwayland module\n"
+#endif
 		"  --modules\t\tLoad the comma-separated list of modules\n"
 		"  --log=FILE\t\tLog to the given file\n"
 		"  -c, --config=FILE\tConfig file to load, defaults to weston.ini\n"
@@ -2876,6 +2878,14 @@ copy_command_line(int argc, char * const argv[])
 	return str;
 }
 
+#if !defined(BUILD_XWAYLAND)
+int
+wet_load_xwayland(struct weston_compositor *comp)
+{
+	return -1;
+}
+#endif
+
 int main(int argc, char *argv[])
 {
 	int ret = EXIT_FAILURE;
@@ -2916,7 +2926,9 @@ int main(int argc, char *argv[])
 		{ WESTON_OPTION_STRING, "shell", 0, &shell },
 		{ WESTON_OPTION_STRING, "socket", 'S', &socket_name },
 		{ WESTON_OPTION_INTEGER, "idle-time", 'i', &idle_time },
+#if defined(BUILD_XWAYLAND)
 		{ WESTON_OPTION_BOOLEAN, "xwayland", 0, &xwayland },
+#endif
 		{ WESTON_OPTION_STRING, "modules", 0, &option_modules },
 		{ WESTON_OPTION_STRING, "log", 0, &log },
 		{ WESTON_OPTION_BOOLEAN, "help", 'h', &help },

compositor/meson.build

@@ -20,6 +20,8 @@ deps_weston = [
 ]
 
 if get_option('xwayland')
+	config_h.set('BUILD_XWAYLAND', '1')
+
 	srcs_weston += 'xwayland.c'
 	config_h.set_quoted('XSERVER_PATH', get_option('xwayland-path'))
 endif