Add DwarfCompileUnit::getSkeleton that returns DwarfCompileUnit* to avoid having to cast from DwarfUnit* on every call.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221031 91177308-0d34-0410-b5e6-96231b3b80d8
Add show and merge tools for sample PGO profiles.

Summary:
This patch extends the 'show' and 'merge' commands in llvm-profdata to handle
sample PGO formats. Using the 'merge' command it is now possible to convert
one sample PGO format to another.

The only format that is currently not working is 'gcc'. I still need to
implement support for it in lib/ProfileData.

The changes in the sample profile support classes are needed for the
merge operation.

Reviewers: bogner

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6065

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221032 91177308-0d34-0410-b5e6-96231b3b80d8
Add '*' to auto variable that is a pointer, as per the coding conventions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221033 91177308-0d34-0410-b5e6-96231b3b80d8
Just iterate the DwarfCompileUnits rather than trying to filter them out of the list of all units.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221034 91177308-0d34-0410-b5e6-96231b3b80d8
And... fix the build some more.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221036 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused function

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221037 91177308-0d34-0410-b5e6-96231b3b80d8