Revert "[llvm-cov] Add support for exporting coverage data to JSON"

This reverts commit r276813. The Windows bots are complaining about some
of the filename regexes in the tests:

  http://bb.pgr.jp/builders/ninja-clang-i686-msc19-R/builds/5299

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276816 91177308-0d34-0410-b5e6-96231b3b80d8
17 files changed