MCDwarf: Sink file/directory creation down into MCDwarfFileTable form MCContext

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203836 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCDwarf.h

@@ -190,6 +190,8 @@ public:
   //
   const MCSymbol *EmitCU(MCStreamer *MCOS) const;
 
+  unsigned getFile(StringRef Directory, StringRef FileName, unsigned FileNumber);
+
   const SmallVectorImpl<std::string> &getMCDwarfDirs() const {
     return MCDwarfDirs;
   }