new port: msp430-elf

[Joseph S. Myers]

I should also add generic new-port comments:

See the checklist under "Back End" in sourcebuild.texi.  In particular, 
add the target to contrib/config-list.mk so all-targets builds cover it.

Make sure that the port builds cleanly when configuring with 
--enable-werror-always and building with a bootstrapped native compiler 
from the same GCC trunk version as you are building.  Make sure this works 
for both 32-bit and 64-bit host compilers, and that those produce the same 
test results (so you don't have bugs depending on whether the host is 
32-bit or 64-bit).

-- 
Joseph S. Myers
joseph@codesourcery.com