GN Mac build work

tools/gn/command_gyp.cc

Index: tools/gn/command_gyp.cc
diff --git a/tools/gn/command_gyp.cc b/tools/gn/command_gyp.cc
index de089d393cfbf7a60ea49a678c56d318a035ae69..3c6bef9daf422f423137b3a845c08917e191098f 100644
--- a/tools/gn/command_gyp.cc
+++ b/tools/gn/command_gyp.cc
@@ -233,9 +233,6 @@ std::pair<int, int> WriteGypFiles(
   for (CorrelatedTargetsMap::iterator i = correlated.begin();
        i != correlated.end(); ++i) {
     const TargetGroup& group = i->second;
-    if (!EnsureTargetsMatch(group, err))
-      return std::make_pair(0, 0);
-
     if (!group.debug->item_node()->should_generate())
       continue;  // Skip non-generated ones.
     if (group.debug->external())
@@ -243,6 +240,9 @@ std::pair<int, int> WriteGypFiles(
     if (group.debug->gyp_file().is_null())
       continue;  // Skip ones without GYP files.
 
+    if (!EnsureTargetsMatch(group, err))
+      return std::make_pair(0, 0);
+
     target_count++;
     grouped_targets[helper.GetGypFileForTarget(group.debug, err)].push_back(
         group);