llvm-profdata: Avoid F_Text in "merge" for now, since "llvm-profdata show" is confused with CRLF.

FIXME: line_iterator should be tolerant of CR.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204540 91177308-0d34-0410-b5e6-96231b3b80d8