Fixed comment in header of Block Frequency Impl and added text for C++ mode.

This is a generic block implementation that works on more than machine blocks.
The C++ mode addition is a bonus due to the extra space provided.

llvm-svn: 186175

llvm/include/llvm/Analysis/BlockFrequencyImpl.h

@@ -1,4 +1,4 @@
-//===---- BlockFrequencyImpl.h - Machine Block Frequency Implementation ---===//
+//===-- BlockFrequencyImpl.h - Block Frequency Implementation --*- C++ -*--===//
 //
 //                     The LLVM Compiler Infrastructure
 //