[analyzer] CmpRuns should include file name in the issue identifier.

This prevents us from treating the issues from different files with the
same function names and same offsets as the same.

The issue identifier now includes the file name. Also added a way to
strip off the root directories form the source file names.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161150 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed