Revert predefined decl tracking.

r158085 added some logic to track predefined declarations.  The main reason we
had predefined declarations in the input was because the __builtin_va_list
declarations were injected into the preprocessor input.  As of r158592 we 
explicitly build the __builtin_va_list declarations.  Therefore the predefined
decl tracking is no longer needed.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158732 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp
index b420c6c..5509f5f 100644
--- a/lib/Lex/Preprocessor.cpp
+++ b/lib/Lex/Preprocessor.cpp
@@ -427,7 +427,7 @@
   llvm::MemoryBuffer *SB =
     llvm::MemoryBuffer::getMemBufferCopy(Predefines, "<built-in>");
   assert(SB && "Cannot create predefined source buffer");
-  FileID FID = SourceMgr.createPredefinesFileIDForMemBuffer(SB);
+  FileID FID = SourceMgr.createFileIDForMemBuffer(SB);
   assert(!FID.isInvalid() && "Could not create FileID for predefines?");
 
   // Start parsing the predefines.