libstdc++: Fix ctype changed after newlib update.

libstdc++: Fix ctype changed after newlib update.

Newlib changed ctype.h recently[1] by moving the short labels from ctype.h intro
the private namespace in ctype_.h.  This broke embedded builds due to them no
longer being found.  Instead they now expose the long names to match glibc.

This patch now uses the short or long names depending on is the short ones are
defined or not.

[1] https://github.com/bminor/newlib/commit/3ba1bd0d9dbc015c14a0aaafcef042f706d1249a

libstdc++-v3/ChangeLog:

	PR libstdc++/103305
	* config/os/newlib/ctype_base.h (upper, lower, alpha, digit, xdigit,
	space, print, graph, cntrl, punct, alnum, blank): Use short or long
	names depending on if short ones are defined.