remove deprecated, unused windows functions

* `CryptAcquireContextA`
 * `CryptReleaseContext`
 * `CryptGenRandom`

See https://github.com/ziglang/zig/issues/534#issuecomment-422208368
15e59eb142Andrew Kelley committed on 9/18/2018, 12:07:48 AMparentb16229d
1 file changedLine totals unavailable