Revert "Retry "[ProfileData] (llvm) Use Error in InstrProf and Coverage, NFC""

This reverts commit r269491. It triggers warnings with Clang, breaking
builds for -Werror users including several build bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269547 91177308-0d34-0410-b5e6-96231b3b80d8
18 files changed