Disable libstdc++ debug mode on GPU bots.

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

 [
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "config",
       "--spec",
       "cache_dir = '[ROOT]/git_cache'\nsolutions = [{'custom_deps': {'src/third_party/WebKit/LayoutTests': None, 'src/webkit/data/layout_tests/LayoutTests': None}, 'custom_vars': {'googlecode_url': 'svn://svn-mirror.golo.chromium.org/%s', 'nacl_trunk': 'svn://svn-mirror.golo.chromium.org/native_client/trunk', 'sourceforge_url': 'svn://svn-mirror.golo.chromium.org/%(repo)s', 'webkit_trunk': 'https://chromium.googlesource.com/chromium/blink.git'}, 'deps_file': '.DEPS.git', 'managed': True, 'name': 'src', 'url': 'https://chromium.googlesource.com/chromium/src.git'}, {'custom_deps': {'src/chrome/test/data/firefox2_profile/searchplugins': None, 'src/chrome/test/data/firefox2_searchplugins': None, 'src/chrome/test/data/firefox3_profile/searchplugins': None, 'src/chrome/test/data/firefox3_searchplugins': None, 'src/chrome/test/data/osdd': None, 'src/chrome/test/data/plugin': None, 'src/chrome/test/data/ssl/certs': None, 'src/data/autodiscovery': None, 'src/data/esctf': None, 'src/data/mach_ports': None, 'src/data/memory_test': None, 'src/data/mozilla_js_tests': None, 'src/data/page_cycler': None, 'src/data/selenium_core': None, 'src/data/tab_switching': None, 'src/tools/grit/grit/test/data': None, 'src/webkit/data/bmp_decoder': None, 'src/webkit/data/ico_decoder': None, 'src/webkit/data/test_shell/plugins': None, 'src/webkit/data/xbm_decoder': None}, 'deps_file': '.DEPS.git', 'managed': True, 'name': 'src-internal', 'url': 'https://chrome-internal.googlesource.com/chrome/src-internal.git'}]"
     ],
@@ skipping 86 matching lines @@
     "name": "gclient recurse (git config user.email)"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
     "env": {
-      "GYP_DEFINES": "clang=1 component=static_library internal_gles2_conform_tests=1 target_arch=ia32",
+      "GYP_DEFINES": "clang=1 component=static_library disable_glibcxx_debug=1 internal_gles2_conform_tests=1 target_arch=ia32",
       "GYP_GENERATORS": "ninja"
     },
     "name": "gclient runhooks"
   },
   {
     "abort_on_failure": true,
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/compile.py",
@@ skipping 357 matching lines @@
       "--test-type=tab_capture_performance_tests",
       "performance_browser_tests",
       "--enable-gpu",
       "--test-launcher-jobs=1",
       "--test-launcher-print-test-stdio=always",
       "--gtest_filter=TabCapturePerformanceTest*"
     ],
     "name": "tab_capture_performance_tests"
   }
 ]