Regenerate sysdeps/mach/configure

[Roland McGrath]

The function definitions suggest that we probably need to add some things
to GLIBC_PROVIDES for the newer autoconf versions.  We probably also ought
to update the version in AC_PREREQ, not because 2.53 won't still work (it
probably will), but just so that we get everybody using the same autoconf
version when they regenerate files to commit.


Thanks,
Roland