Build and install LLVM gold plugin on Linux.

tools/clang/plugins/ChromeClassTester.cpp

Index: tools/clang/plugins/ChromeClassTester.cpp
diff --git a/tools/clang/plugins/ChromeClassTester.cpp b/tools/clang/plugins/ChromeClassTester.cpp
index 9cbc84a4e2691ccc4c64a94d10931b1463bcb1c3..48d6a735f272c3db2331e7f21703fedaa265e0a2 100644
--- a/tools/clang/plugins/ChromeClassTester.cpp
+++ b/tools/clang/plugins/ChromeClassTester.cpp
@@ -149,7 +149,10 @@ void ChromeClassTester::BuildBannedLists() {
   banned_directories_.push_back("/courgette/");
   banned_directories_.push_back("/pdf/");
   banned_directories_.push_back("/ppapi/");
-  banned_directories_.push_back("/usr/");
+  banned_directories_.push_back("/usr/include/");
+  banned_directories_.push_back("/usr/lib/");
+  banned_directories_.push_back("/usr/local/include/");
+  banned_directories_.push_back("/usr/local/lib/");
   banned_directories_.push_back("/testing/");
   banned_directories_.push_back("/v8/");
   banned_directories_.push_back("/dart/");
@@ -263,11 +266,6 @@ bool ChromeClassTester::InBannedDirectory(SourceLocation loc) {
     filename = resolvedPath;
   }
 
-  // On linux, chrome is often checked out to /usr/local/google. Due to the
-  // "usr" rule in banned_directories_, all diagnostics would be suppressed
-  // in that case. As a workaround, strip that prefix.
-  filename = lstrip(filename, "/usr/local/google");
-
   for (size_t i = 0; i < banned_directories_.size(); ++i) {
     // If any of the banned directories occur as a component in filename,
     // this file is rejected.