Add inline stack streaming to binary sample profiles.

Add inline stack streaming to binary sample profiles.

With this patch we can now read and write inline stacks in sample
profiles to the binary encoded profiles.

In a subsequent patch, I will add a string table to the binary encoding.
Right now function names are emitted as strings every time we find them.
This is too bloated and will produce large files in applications with
lots of inlining.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249861 91177308-0d34-0410-b5e6-96231b3b80d8