This will fix `tests::sign` test case on mips/mips64. Verified with
`cross`[1] tool.
cross test --target mips-unknown-linux-gnu
cross test --target mips64el-unknown-linux-gnuabi64
Unfortunately this fix doesn't make `tests::test_debug_output` test case
pass, but this is about debug output so its not as critical as this
patch. See #63 for a discussion.
[1]: https://github.com/japaric/rust-cross
Pieter moved some stuff I need into the contrib/ directory which does
not expose anything through the shared lib, so I need to statically
link.
I might also use this to do evil things to expose the SHA256 code
in libsecp, but not for now ;).