Added support for the Builtin attribute.

The Builtin attribute is an attribute that can be placed on function call site that signal that even though a function is declared as being a builtin,

rdar://problem/13727199

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185049 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index 82d9975..1b5422e 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -563,6 +563,7 @@
   KEYWORD(attributes);
 
   KEYWORD(alwaysinline);
+  KEYWORD(builtin);
   KEYWORD(byval);
   KEYWORD(cold);
   KEYWORD(inlinehint);