Enable --salvage-unused-profile for AutoFDO

Additionally enable --salvage-unused-profile, to allow the compiler to
identify and fix profile mismatches due to renamed functions.

This functionality was added to Clang in https://github.com/llvm/llvm-project/pull/95135.

Test: presubmit
Change-Id: I7f441e88409cb29eea746c281af2f7874df1688c