[PGO] Differentiate Clang instrumentation and IR level instrumentation profiles

This patch uses one bit in profile version to differentiate Clang
instrumentation and IR level instrumentation profiles.

PGOInstrumenation generates a COMDAT variable __llvm_profile_raw_version so
that the compiler runtime can set the right profile kind.
PGOInstrumenation now checks this bit to make sure it's an IR level
instrumentation profile.

Differential Revision: http://reviews.llvm.org/D15540

llvm-svn: 260146