Don't worry about using IRIX 5.3's wctype.h broken definitions;

Don't worry about using IRIX 5.3's wctype.h broken definitions;
simply work around them.
* lib/wctype_.h: Remove test for HAVE_WCTYPE_CTMP_BUG.
(iswalnum, iswalpha, iswblank, iswcntrl, iswdigit, iswgraph, iswlower):
(iswprint, iswpunct, iswspace, iswupper, iswxdigit): Undef before declaring.
Don't bother to define as macros, since the standard doesn't require it.
* m4/wctype.m4 (WCTYPE_H, ABSOLUTE_WCTYPE_H): Simplify, since we no
longer worry about IRIX 5.3.
(HAVE_WCTYPE_CTMP_BUG): Remove.