Trigonometric optimizations for POWER cpus

These POWER optimizations remove most of the FP->INT conversions in
hypot/hypotf and sinf/cosf on POWER making the computation done with
FP operations instead.  This eliminates Load-Hit-Store (LHS) stalls,
increasing performance of hypot/hypotf (by about 100% on POWER7 and
12% on POWER6) and sinf/cosf (by 80% on POWER7 and 30% on POWER6).