This patch adds support in profile runtime to allow user change the root directory of the profile. It uses a machanism compatible to libgcc: GCOV_PREFIX and GCOV_PREFIX_STRIP.
It also helps users to easily migrate to use LLVM PGO.
Lgtm, although I think the line-wrapping on the added RUN lines needs to be corrected.
Nit: the call is sunk to the branch, why not getting rid of SelectPat and PNS variable?
Also to the third calls.
Addressed review feedback.