Also look for headers in /url in mod_pagespeed tree (#1264)

This is needed because the current GURL implementation there --- and hence
google_url.h needs an extra compat header that's there.
diff --git a/config b/config
index 9257b12..d9c6cfc 100644
--- a/config
+++ b/config
@@ -167,7 +167,8 @@
   $mod_pagespeed_dir/third_party/apr/src/include \
   $mod_pagespeed_dir/third_party/aprutil/src/include \
   $mod_pagespeed_dir/third_party/apr/gen/arch/$os_name/$arch_name/include \
-  $mod_pagespeed_dir/third_party/aprutil/gen/arch/$os_name/$arch_name/include"
+  $mod_pagespeed_dir/third_party/aprutil/gen/arch/$os_name/$arch_name/include \
+  $mod_pagespeed_dir/url"
 ngx_feature_path="$pagespeed_include"
 
 pagespeed_libs="$pagespeed_libs $psol_binary -lrt -pthread -lm"