Basic: import IntrusiveRefCntPtr<> into clang namespace

The class name is long enough without the llvm:: added.
Also bring in RefCountedBase and RefCountedBaseVPTR.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150958 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/driver/cc1_main.cpp b/tools/driver/cc1_main.cpp
index e491d61..a211090 100644
--- a/tools/driver/cc1_main.cpp
+++ b/tools/driver/cc1_main.cpp
@@ -118,7 +118,7 @@
 int cc1_main(const char **ArgBegin, const char **ArgEnd,
              const char *Argv0, void *MainAddr) {
   OwningPtr<CompilerInstance> Clang(new CompilerInstance());
-  llvm::IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
+  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
 
   // Run clang -cc1 test.
   if (ArgBegin != ArgEnd && StringRef(ArgBegin[0]) == "-cc1test") {