Split Finish into Finish and FinishImpl to have a common place to do end of

file error checking. Use that to error on an unfinished cfi_startproc.

The error is not nice, but is already better than a segmentation fault.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147717 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PTX/PTXMCAsmStreamer.cpp

@@ -176,7 +176,7 @@ public:
   /// indicated by the hasRawTextSupport() predicate.
   virtual void EmitRawText(StringRef String);
 
-  virtual void Finish();
+  virtual void FinishImpl();
 
   /// @}
 
@@ -540,7 +540,7 @@ void PTXMCAsmStreamer::EmitRawText(StringRef String) {
   EmitEOL();
 }
 
-void PTXMCAsmStreamer::Finish() {}
+void PTXMCAsmStreamer::FinishImpl() {}
 
 namespace llvm {
   MCStreamer *createPTXAsmStreamer(MCContext &Context,