Try to fix clang plugin tests after https://codereview.chromium.org/2270433002/

BUG=none
TBR=thestig@chromium.org
NOTRY=true

Review-Url: https://codereview.chromium.org/2298013004
Cr-Commit-Position: refs/heads/master@{#415755}

tools/clang/plugins/tests/test.py

@@ -19,7 +19,6 @@ class ChromeStylePluginTest(plugin_testing.ClangPluginTest):
   """Test harness for the Chrome style plugin."""
 
   def AdjustClangArguments(self, clang_cmd):
-    self.AddPluginArg(clang_cmd, 'follow-macro-expansion')
     clang_cmd.extend([
         # Skip code generation
         '-fsyntax-only',