[PGO] Check that PGOOpt exists before using PGOOpt->ColdOptType (#89139)

This means that the pass is unusable without some sort of profile. We
can revisit this decision later if we want to support running this pass
without a profile.

GitOrigin-RevId: 947b656add053a8c9a36cab27b5c6e8eb9c426f7
2 files changed