Added GYP defines to dump linux symbols for gpu perf bots and trybots.

scripts/slave/recipes/gpu/build_and_test.expected/killall_gnome_keyring_failure.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
     "name": "cleanup temp"
   },
   {
@@ skipping 59 matching lines @@
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
     "env": {
-      "GYP_DEFINES": "archive_gpu_tests=1 blink_logging_always_on=1 component=static_library dcheck_always_on=1 disable_glibcxx_debug=1 ffmpeg_branding=Chrome gomadir='[BUILD]/goma' internal_gles2_conform_tests=1 proprietary_codecs=1 target_arch=x64 test_isolation_mode=prepare use_goma=1"
+      "GYP_DEFINES": "archive_gpu_tests=1 blink_logging_always_on=1 component=static_library dcheck_always_on=1 disable_glibcxx_debug=1 ffmpeg_branding=Chrome gomadir='[BUILD]/goma' internal_gles2_conform_tests=1 linux_dump_symbols=1 proprietary_codecs=1 target_arch=x64 test_isolation_mode=prepare use_goma=1"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[isolate]/resources/find_isolated_tests.py",
       "--build-dir",
       "[SLAVE_BUILD]/src/out/Release",
@@ skipping 854 matching lines @@
       "[SLAVE_BUILD]/src/tools/swarming_client/run_isolated.py",
       "-H",
       "[dummy hash for media_unittests]",
       "-I",
       "https://isolateserver.appspot.com",
       "--"
     ],
     "name": "media_unittests"
   }
 ]