[PATCH] [libcxx] Add numerous options to libc++ LIT test suite configuration.

[Eric Fiselier]

Thanks for the information on the default clang tidy settings, I wasn't quite sure what to use :D

The reason I didn't use a clang-tidy is because much of the clang-tidy invocation is sensative to information that could change from run to run due to different configurations.
I'll take a look into it further to see if there is any information that is consistent.

http://reviews.llvm.org/D5877