The build.rd script tries to find an android toolchain but fails on
other OS, such as the BSDs, that do not provide one.  This change
simply marks them as "unknown" and fails to build with an unknown
android toolchain, but succeeds to build the regular crate on the any
other OS natively.  The fix is not specific to OpenBSD as it unbreaks
all OS that are not linux, windows, or macos.

* Don't use deprecated rustc-serialize

* Don't depend on libc

Replace `gcc` with a newer `cc` crate

`libsecp` update and some minor enhancements

build secp256 on android

Added methods for secretstore implementation

Add curve points (combine public keys) exposed

Andrew Poelstra authored Aug 07, 2016 and Arkadiy Paronyan committed Aug 20, 2016

Turns out you cannot initialize constant SecretKeys in any way; these
two constants should cover most sane use cases (other good choices
are the SECG generator and the Alpha CT generator, but these will
wait for a major CT-supporting upgrade, unless demand for them appears.)

merge with apoelstra/master

cleanup

add #[repr(C)] to SecretKey, SharedSecret

Bump libc

Bumping libc

Removed unused attributes