Revised to use file list path as reference path, or path provide by new -prefix option.  Revised to use LLVM option parser.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@177959 91177308-0d34-0410-b5e6-96231b3b80d8
Added simple regression test for modularize.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@177960 91177308-0d34-0410-b5e6-96231b3b80d8