This changeset is modeled after Intel's submission for SVML. It enables trigonometry functions vectorization via SLEEF: http://sleef.org/.

- A new vectorization library enum is added to TargetLibraryInfo.h: SLEEF.

- A new option is added to TargetLibraryInfoImpl - ClVectorLibrary: SLEEF.

- A comprehensive test case is included in this changeset.

- In a separate changeset (for clang), a new vectorization library argument is added to -fveclib: -fveclib=SLEEF.

Trigonometry functions that are vectorized by sleef:

acos

asin

atan

atanh

cos

cosh

exp

exp2

exp10

lgamma

log10

log2

log

sin

sinh

sqrt

tan

tanh

tgamma