use more specific variables in net/BUILD.gn

net/BUILD.gn

Index: net/BUILD.gn
diff --git a/net/BUILD.gn b/net/BUILD.gn
index 5d9801b21ae33cbd2a2070c8821bd35a15a7bc40..fae9f3dab21f947d075992429161f1ff73aa5fb1 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -1007,12 +1007,16 @@ if (!is_ios && !is_android) {
       ]
 
       if (is_desktop_linux) {
-        configs += [
-          "//build/config/linux:gconf",
-          "//build/config/linux:glib",
-        ]
         deps += [ "//build/config/linux:gio" ]
       }
+
+      if (use_gconf) {
+        configs += [ "//build/config/linux:gconf" ]
+      }
+
+      if (use_glib) {
+        configs += [ "//build/config/linux:glib" ]
+      }
     }
   }