Bug 995089 - GIO support shouldn't check GTK2 version if GTK3 build. r=glandium

configure.in

@@ -4821,8 +4821,11 @@ then
 
     if test "$MOZ_ENABLE_GIO" -a "$MOZ_ENABLE_GTK"
     then
-        PKG_CHECK_MODULES(_GTKCHECK, gtk+-2.0 >= 2.14, ,
-                          [AC_MSG_ERROR([* * * Could not find gtk+-2.0 > 2.14. Required for build with gio.])])
+        if test "$MOZ_ENABLE_GTK2"
+        then
+            PKG_CHECK_MODULES(_GTKCHECK, gtk+-2.0 >= 2.14, ,
+                              [AC_MSG_ERROR([* * * Could not find gtk+-2.0 > 2.14. Required for build with gio.])])
+        fi
         PKG_CHECK_MODULES(MOZ_GIO, gio-2.0 >= $GIO_VERSION,[
             MOZ_GIO_LIBS=`echo $MOZ_GIO_LIBS | sed 's/-llinc\>//'`
             MOZ_ENABLE_GIO=1