[gjs] build: Don't error out on missing cairo-xlib.pc

[Philip Chimento <pchimento src gnome org>]

commit ee27166e207e6edb319973a8324bed816454efcc
Author: Philip Chimento <philip chimento gmail com>
Date:   Tue Sep 30 23:39:03 2014 -0700

    build: Don't error out on missing cairo-xlib.pc
    
    When building on OSX, we would be using Cairo without XLib support, so
    instead of erroring out if pkg-config can't find cairo-xlib, print a
    warning. The X-based code will not be used anyway if Cairo hasn't
    detected XLib.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=737701

 configure.ac |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index d6d0a86..1454f53 100644
--- a/configure.ac
+++ b/configure.ac
@@ -99,7 +99,8 @@ AM_CONDITIONAL(ENABLE_CAIRO, test x$have_cairo = xyes)
 AS_IF([test x$have_cairo = xyes], [
   AC_DEFINE([ENABLE_CAIRO],[1],[Define if you want to build with cairo support])
 ])
-PKG_CHECK_MODULES([GJS_CAIRO_XLIB], [cairo-xlib], , )
+PKG_CHECK_MODULES([GJS_CAIRO_XLIB], [cairo-xlib], [],
+  [AC_MSG_WARN([Cairo-xlib support not found])])
 
 # Optional GTK+ dep (enabled by default)
 AC_ARG_WITH(gtk,