setlocale() on Windows doesn't work correctly if the locale name contains

dots. I previously worked around this in initdb, mapping the known
problematic locale names to aliases that work, but Hiroshi Inoue pointed
out that that's not enough because even if you use one of the aliases, like
"Chinese_HKG", setlocale(LC_CTYPE, NULL) returns back the long form, ie.
"Chinese_Hong Kong S.A.R.". When we try to restore an old locale value by
passing that value back to setlocale(), it fails. Note that you are affected
by this bug also if you use one of those short-form names manually, so just
reverting the hack in initdb won't fix it.

To work around that, move the locale name mapping from initdb to a wrapper
around setlocale(), so that the mapping is invoked on every setlocale() call.

Also, add a few checks for failed setlocale() calls in the backend. These
calls shouldn't fail, and if they do there isn't much we can do about it,
but at least you'll get a warning.

Backpatch to 9.1, where the initdb hack was introduced. The Windows bug
affects older versions too if you set locale manually to one of the aliases,
but given the lack of complaints from the field, I'm hesitent to backpatch.

src/include/port.h

@@ -226,16 +226,27 @@ __attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
 #endif
 #endif   /* USE_REPL_SNPRINTF */
 
+#if defined(WIN32)
 /*
  * Versions of libintl >= 0.18? try to replace setlocale() with a macro
  * to their own versions.  Remove the macro, if it exists, because it
  * ends up calling the wrong version when the backend and libintl use
  * different versions of msvcrt.
  */
-#if defined(setlocale) && defined(WIN32)
+#if defined(setlocale)
 #undef setlocale
 #endif
 
+/*
+ * Define our own wrapper macro around setlocale() to work around bugs in
+ * Windows' native setlocale() function.
+ */
+extern char *pgwin32_setlocale(int category, const char *locale);
+
+#define setlocale(a,b) pgwin32_setlocale(a,b)
+
+#endif   /* WIN32 */
+
 /* Portable prompt handling */
 extern char *simple_prompt(const char *prompt, int maxlen, bool echo);