* optabs.h (enum optab_index): Add new OTI_pow and OTI_atan2.
(pow_optab, atan2_optab): Define corresponding macros.
* optabs.c (init_optabs): Initialize pow_optab and atan2_optab.
* genopinit.c (optabs): Implement pow_optab and atan2_optab
using pow?f3 and atan2?f3 patterns.
* builtins.c (expand_errno_check): New function to update errno
if necessary, split out from expand_builtin_mathfn.
(expand_builtin_mathfn): Use expand_errno_check.
(expand_builtin_mathfn_2): New function to handle expanding binary
math functions, reusing the code in expand_errno_check.
(expand_builtin): Handle the pow and atan2 math built-ins,
BUILT_IN_{POW,POWF,POWL,ATAN2,ATAN2F,ATAN2L} via the new function
expand_builtin_mathfn_2.
* doc/md.texi: Document new pow?f3 and atan2?f3 patterns.
From-SVN: r62708
