Revert "Adapt gcov to changes in CFE."

This reverts commit r348203.
Reason: this produces absolute paths in .gcno files, breaking us
internally as we rely on them being consistent with the filenames passed
in the command line.

Also reverts r348157 and r348155 to account for revert of r348154 in
clang repository.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348279 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed