[gtk+] Fix build with explicit --enable-wayland-backend

[Matthias Clasen <matthiasc src gnome org>]

commit fe4fdeb7ae9b7d7fb6c10bf498a2b3c5b93730ca
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Oct 6 15:32:18 2013 -0400

    Fix build with explicit --enable-wayland-backend
    
    We forgot to set set WAYLAND_SCANNER in this case.

 configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index de92e7a..73a2c47 100644
--- a/configure.ac
+++ b/configure.ac
@@ -419,6 +419,7 @@ if test "$enable_wayland_backend" = "yes"; then
 #define GDK_WINDOWING_WAYLAND"
   DISABLE_ON_WAYLAND='%'
   WAYLAND_PACKAGES="$WAYLAND_DEPENDENCIES"
+  AC_PATH_PROG([WAYLAND_SCANNER],[wayland-scanner],[no])
   AS_IF([test "x$WAYLAND_SCANNER" = "xno"],
     AC_MSG_ERROR([Could not find wayland-scanner in your PATH, required for parsing wayland extension 
protocols]))
   AC_SUBST([WAYLAND_SCANNER])