Remove configure probe for wctype.h.

This header is present in SUSv2 and Windows.

Also remove the inclusion of <wchar.h>, following clues that it was only
included for the benefit of historical systems that didn't have
<wctype.h>.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CA%2BhUKGKAmTgbg_hMiGG5T7pkpzOnY1cWFAHYtZXHCpqeC_hCkA%40mail.gmail.com

src/backend/utils/adt/formatting.c

@@ -69,15 +69,7 @@
 #include <math.h>
 #include <float.h>
 #include <limits.h>
-
-/*
- * towlower() and friends should be in <wctype.h>, but some pre-C99 systems
- * declare them in <wchar.h>, so include that too.
- */
-#include <wchar.h>
-#ifdef HAVE_WCTYPE_H
 #include <wctype.h>
-#endif
 
 #ifdef USE_ICU
 #include <unicode/ustring.h>

src/include/pg_config.h.in

@@ -700,9 +700,6 @@
 /* Define to 1 if you have the `wcstombs_l' function. */
 #undef HAVE_WCSTOMBS_L
 
-/* Define to 1 if you have the <wctype.h> header file. */
-#undef HAVE_WCTYPE_H
-
 /* Define to 1 if you have the <winldap.h> header file. */
 #undef HAVE_WINLDAP_H
 

src/include/regex/regcustom.h

@@ -40,15 +40,7 @@
 
 #include <ctype.h>
 #include <limits.h>
-
-/*
- * towlower() and friends should be in <wctype.h>, but some pre-C99 systems
- * declare them in <wchar.h>, so include that too.
- */
-#include <wchar.h>
-#ifdef HAVE_WCTYPE_H
 #include <wctype.h>
-#endif
 
 #include "mb/pg_wchar.h"
 

src/include/tsearch/ts_locale.h

@@ -14,20 +14,12 @@
 
 #include <ctype.h>
 #include <limits.h>
+#include <wctype.h>
 
 #include "lib/stringinfo.h"
 #include "mb/pg_wchar.h"
 #include "utils/pg_locale.h"
 
-/*
- * towlower() and friends should be in <wctype.h>, but some pre-C99 systems
- * declare them in <wchar.h>, so include that too.
- */
-#include <wchar.h>
-#ifdef HAVE_WCTYPE_H
-#include <wctype.h>
-#endif
-
 /* working state for tsearch_readline (should be a local var in caller) */
 typedef struct
 {

src/tools/msvc/Solution.pm

@@ -426,7 +426,6 @@ sub GenerateFiles
 		HAVE_UUID_UUID_H                         => undef,
 		HAVE_WINLDAP_H                           => undef,
 		HAVE_WCSTOMBS_L                          => 1,
-		HAVE_WCTYPE_H                            => 1,
 		HAVE_VISIBILITY_ATTRIBUTE                => undef,
 		HAVE_WRITEV                              => undef,
 		HAVE_X509_GET_SIGNATURE_NID              => 1,