Add cross-compilation results for GNU/Hurd.

Add cross-compilation results for GNU/Hurd.

* m4/calloc.m4: Add GNU/Hurd guess.
* m4/cbrtl.m4: Likewise.
* m4/ceil.m4: Likewise.
* m4/ceilf.m4: Likewise.
* m4/ceill.m4: Likewise.
* m4/chown.m4: Likewise.
* m4/duplocale.m4: Likewise.
* m4/exp2l.m4: Likewise.
* m4/expm1.m4: Likewise.
* m4/fchdir.m4: Likewise.
* m4/floor.m4: Likewise.
* m4/floorf.m4: Likewise.
* m4/fmod.m4: Likewise.
* m4/fmodf.m4: Likewise.
* m4/fmodl.m4: Likewise.
* m4/getcwd.m4: Likewise.
* m4/getgroups.m4: Likewise.
* m4/gettimeofday.m4: Likewise.
* m4/hypot.m4: Likewise.
* m4/hypotf.m4: Likewise.
* m4/hypotl.m4: Likewise.
* m4/link-follow.m4: Likewise.
* m4/link.m4: Likewise.
* m4/linkat.m4: Likewise.
* m4/log.m4: Likewise.
* m4/log10.m4: Likewise.
* m4/log10f.m4: Likewise.
* m4/log1p.m4: Likewise.
* m4/log1pf.m4: Likewise.
* m4/log1pl.m4: Likewise.
* m4/log2.m4: Likewise.
* m4/log2f.m4: Likewise.
* m4/logf.m4: Likewise.
* m4/lstat.m4: Likewise.
* m4/malloc.m4: Likewise.
* m4/mbrlen.m4: Likewise.
* m4/mbrtowc.m4: Likewise.
* m4/mkdir.m4: Likewise.
* m4/mkfifo.m4: Likewise.
* m4/mknod.m4: Likewise.
* m4/mkstemp.m4: Likewise.
* m4/modf.m4: Likewise.
* m4/modff.m4: Likewise.
* m4/modfl.m4: Likewise.
* m4/printf.m4: Likewise.
* m4/pselect.m4: Likewise.
* m4/ptsname.m4: Likewise.
* m4/putenv.m4: Likewise.
* m4/readlink.m4: Likewise.
* m4/realloc.m4: Likewise.
* m4/remainder.m4: Likewise.
* m4/remainderf.m4: Likewise.
* m4/remainderl.m4: Likewise.
* m4/rmdir.m4: Likewise.
* m4/round.m4: Likewise.
* m4/roundf.m4: Likewise.
* m4/roundl.m4: Likewise.
* m4/select.m4: Likewise.
* m4/setenv.m4: Likewise.
* m4/signbit.m4: Likewise.
* m4/sleep.m4: Likewise.
* m4/stat.m4: Likewise.
* m4/strerror.m4: Likewise.
* m4/strtok_r.m4: Likewise.
* m4/symlink.m4: Likewise.
* m4/symlinkat.m4: Likewise.
* m4/trunc.m4: Likewise.
* m4/truncf.m4: Likewise.
* m4/truncl.m4: Likewise.
* m4/tzset.m4: Likewise.
* m4/ungetc.m4: Likewise.
* m4/usleep.m4: Likewise.
* m4/wcwidth.m4: Likewise.