initial support for s390x
A new target, `s390x-unknown-linux-gnu`, has been added to the compiler
and can be used to build no_core/no_std Rust programs.
Known limitations:
- librustc_trans/cabi_s390x.rs is missing. This means no support for
`extern "C" fn`.
- No support for this arch in libc. This means std can't be cross
compiled for this target.
r? @alexcrichton
This time I couldn't test running a binary cross compiled to this target under QEMU because the qemu-s390x that ships with Ubuntu 16.04 SIGABRTs with every s390x binary I run it with.
Change in binary size of `librustc_llvm.so`:
Without this commit (stage1): 41895736 bytes
With this commit (stage1): 42899016 bytes
~2.4% increase
78a0838756