configure: Adds --with-xwayland-path option

This adds a --with-xwayland-path configure option that can be used to
specify the absolute path of a headless X server binary supporting
the wayland xserver protocol.

configure.ac

@@ -128,6 +128,11 @@ AC_ARG_WITH([wayland-protocols],
             ],
             [])
 
+AC_ARG_WITH([xwayland-path],
+            [AS_HELP_STRING([--with-xwayland-path], [Absolute path for an X Wayland server])],
+            [XWAYLAND_PATH="$withval"],
+            [XWAYLAND_PATH="$bindir/Xorg"])
+
 AM_GLIB_GNU_GETTEXT
 
 ## here we get the flags we'll actually use
@@ -235,6 +240,8 @@ if test x$enable_wayland = "xyes"; then
         AC_MSG_ERROR([Could not find wayland-scanner in your PATH, required for parsing wayland extension protocols]))
   AC_SUBST([WAYLAND_SCANNER])
 
+  AC_SUBST(XWAYLAND_PATH)
+
   MUTTER_PC_MODULES="$MUTTER_PC_MODULES wayland-server clutter-wayland-compositor-1.0"
   AC_DEFINE(HAVE_WAYLAND, , [Building with Wayland support])
   have_wayland=yes

src/Makefile.am

@@ -29,6 +29,12 @@ INCLUDES=								\
 	-DMUTTER_PLUGIN_DIR=\"@MUTTER_PLUGIN_DIR@\"			\
 	-DGETTEXT_PACKAGE=\"$(GETTEXT_PACKAGE)\"
 
+if HAVE_WAYLAND
+INCLUDES += \
+	-I$(srcdir)/wayland						\
+	-DXWAYLAND_PATH='"@XWAYLAND_PATH@"'
+endif
+
 mutter_built_sources = \
 	mutter-enum-types.h \
 	mutter-enum-types.c