[clang-tidy] Support relative paths in run-clang-tidy.py
[clang-tidy] Support relative paths in run-clang-tidy.py

Unfortunately, these python scripts are not tested currently. I did the testing
manually on LLVM by editing the CMake generated compilation database to
contain relative paths for some of the files. 

Differential Revision: https://reviews.llvm.org/D39603


git-svn-id: a34e9779ed74578ad5922b3306b3d80a0c825546@317468 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra