More ProfileInfo improvements.

More ProfileInfo improvements.
 - Part of optimal static profiling patch sequence by Andreas Neustifter.

 - Store edge, block, and function information separately for each functions
   (instead of in one giant map).

 - Return frequencies as double instead of int, and use a sentinel value for
   missing information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78477 91177308-0d34-0410-b5e6-96231b3b80d8