This updates Gnulib to v0.0-4219-g84cdd8b.
* m4/gnulib-cache.m4: Add `isinf' and `isnan'.
* configure.ac: Remove checks for `floatingpoint.h', `ieeefp.h', and
`nan.h'.
* libguile/gen-scmconfig.c (main): Remove definitions of
`SCM_HAVE_FLOATINGPOINT_H', `SCM_HAVE_IEEEFP_H', and
`SCM_HAVE_NAN_H'.
* libguile/numbers.c (isnan)[SCO && !HAVE_ISNAN]: Remove.
(isinf)[SCO && !HAVE_ISINF]: Remove.
(xisinf, xisnan): Remove. Change callers to use `isinf' and `isnan'.
(guile_ieee_init): Remove the `defined HAVE_ISINF' and `define
HAVE_ISNAN' conditions.
* libguile/numbers.h: Remove code conditional on
`SCM_HAVE_FLOATINGPOINT_H', `SCM_HAVE_IEEEFP_H', or `SCM_HAVE_NAN_H'.
