libclc now has a build system

Hi all,

I have just committed new directory layout and build system for libclc.
The build system will build a builtins.bc for the ptx32 and ptx64
architectures. The compile-test.sh script has also been updated to
cause test programs to link with builtins.bc (eventually this will
become part of the Clang driver).

Usage is:

./configure.py --with-llvm-config=/path/to/llvm-config && make

You need a very recent LLVM/Clang (r143316 or later) for the
compile-test.sh script to work.

Thanks,