Flip CQ builders that are building 'all' to 'gn_all'.

testing/buildbot/chromium.win.json

 {
   "Win 7 Tests x64 (1)": {
     "gtest_tests": [
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "accessibility_unittests"
       },
       {
@@ skipping 2310 matching lines @@
         },
         "test": "content_browsertests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "events_unittests"
       }
     ]
+  },
+  "WinClang64 (dbg)": {
+    "additional_compile_targets": [
+      "gn_all"
+    ]
   }
 }