Preprocessor: Allocate MacroInfo objects using a BumpPtrAllocator instead using new/delete.  This speeds up -Eonly on Cocoa.h using the regular lexer by 1.8% and the PTHLexer by 3%.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61042 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index 3ce3581..81e44f4 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -42,7 +42,7 @@
   IdentifierInfo *Id = getIdentifierInfo(Name);
   
   // Mark it as being a macro that is builtin.
-  MacroInfo *MI = new MacroInfo(SourceLocation());
+  MacroInfo *MI = AllocateMacroInfo(SourceLocation());
   MI->setIsBuiltinMacro();
   setMacroInfo(Id, MI);
   return Id;