real.c (mpfr_from_real): Handle Inf and NaN, and allow the rounding mode to be specified by the caller.

* real.c (mpfr_from_real): Handle Inf and NaN, and allow the
rounding mode to be specified by the caller.
(real_to_mpfr) Likewise.
* real.h: Update mpfr_from_real, mpfr_to_real prototypes to
include new arguments.
* builtins.c: Update mpfr_from_real, mpfr_to_real calls.

From-SVN: r124139