[SystemZ] Add support for new cpu architecture - arch13

This patch series adds support for the next-generation arch13
CPU architecture to the SystemZ backend.

This includes:
- Basic support for the new processor and its features.
- Support for low-level builtins mapped to new LLVM intrinsics.
- New high-level intrinsics in vecintrin.h.
- Indicate support by defining  __VEC__ == 10303.

Note: No currently available Z system supports the arch13
architecture.  Once new systems become available, the
official system name will be added as supported -march name.

llvm-svn: 365933