* libm/math/e_pow.c: Fix to be consistent with glibc with regards
to treatment of NaN and +-inf arguments.
* libm/math/ef_pow.c: Ditto.
* libm/math/w_pow.c: Ditto.
* libm/math/wf_pow.c: Ditto.
* libm/math/w_acos.c: Fix domain errors to return NaN.
* libm/math/w_asin.c: Ditto.
* libm/math/wf_acos.c: Ditto.
* libm/math/wf_asin.c: Ditto.
* libm/math/w_log.c: Fix to return NaN for negative number inputs.
* libm/math/wf_log.c: Ditto.
* libm/math/wf_log10.c: Ditto.
* libm/math/w_log10.c: Ditto.
* libm/math/e_pow.c (__ieee754_pow): Fix case whereby
x is close to -1.0 and y is very large to use ax (absolute value)
instead of x.
* libm/math/ef_pow.c (__ieee754_powf): Ditto.