First tiny move towards integrating AddressSanitizer regressions test into...

First tiny move towards integrating AddressSanitizer regressions test into LLVM lit-based testing infrastructure.
The goal is to be able to run ASan tests by simply running "make check-asan" command from CMake build tree:
* tests should use fresh clang binary from current build tree.
* tests should use the same RUN-lines syntax as llvm/clang reg tests.

Next steps:
- restricting tests to machines where target is equal to host, i.e. where we can produce working binaries.
- moving AddressSanitizer unit tests to lit as well.

llvm-svn: 161050