isprint(3)

[YONETANI Tomokazu <qhwt+dfly@xxxxxxxxxx>]

Hello.
On post-Citrus-import system, isprint('\t') returns true even for
C locale. This contradicts with what's explained in isprint(3) man page.
This also slightly affects tools like hd(1):

[on pre-Citrus system]
$ printf 'abc\tdef' | LANG=C hd -v
00000000  61 62 63 09 64 65 66                              |abc.def|
00000007
[on post-Citrus system]
$ printf 'abc\tdef' | LANG=C hd -v
00000000  61 62 63 09 64 65 66                              |abc	def|
00000007