[PGO] Move value profile format related structures and APIs to common file

[PGO] Move value profile format related structures and APIs to common file

This is the last step to enable profile runtime to share the same value prof
data format and reader/writer code with llvm host tools. The VP related
data structures are moved to a section in InstrProfData.inc enabled with macro
INSTR_PROF_VALUE_PROF_DATA, and common API implementations are enabled with
INSTR_PROF_COMMON_API_IMPL. There should be no functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254235 91177308-0d34-0410-b5e6-96231b3b80d8