x86: implemented roundings for SSE4.1 (#158)
x86: implemented roundings for SSE4.1 (#158)

* x86: implemented roundings for SSE4.1

* x86: sse41 roundings - added docs and fixed assert__* tests

rust-lang/stdarch,rust-lang/stdarch,rust-lang/stdarch,rust-lang/stdarch,rust-lang/stdarch