Cygwin: regex: fix faulty check for valid range expression

Cygwin: regex: fix faulty check for valid range expression

Except for the "C" or "POSIX" locale, checking for start <= finish
is always wrong.  Range start must be <= range finish in terms of the
locale's collating order.  So make sure to call always wcscoll(), even
in the "C"/"POSIX" locale, which makes wcscoll equivalent to wcscmp
anyway.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>