Simplify gettimeofday() fallback logic.

There's no known supported system needing 1 argument gettimeofday()
support. The test for it was added a long time ago (92c6bf9775). Remove.

Until now we tested whether a gettimeofday() fallback is needed when
targetting windows. Which lead to the odd result that HAVE_GETTIMEOFDAY only
being defined when targetting MinGW (which has gettimeofday() since at least
2007). As the fallback is specific to msvc, remove the configure code and
rename src/port/gettimeofday.c to src/port/win32gettimeofday.c.

While at it, also remove the definition of struct timezone, a forward
declaration of the struct is sufficient.

Reviewed-By: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220806000311.ywx65iuchvj4qn2k@awork3.anarazel.de

src/include/pg_config.h.in

@@ -55,13 +55,6 @@
    (--enable-thread-safety) */
 #undef ENABLE_THREAD_SAFETY
 
-/* Define to 1 if gettimeofday() takes only 1 argument. */
-#undef GETTIMEOFDAY_1ARG
-
-#ifdef GETTIMEOFDAY_1ARG
-# define gettimeofday(a,b) gettimeofday(a)
-#endif
-
 /* Define to 1 if you have the `append_history' function. */
 #undef HAVE_APPEND_HISTORY
 
@@ -215,9 +208,6 @@
 /* Define to 1 if you have the `getpeerucred' function. */
 #undef HAVE_GETPEERUCRED
 
-/* Define to 1 if you have the `gettimeofday' function. */
-#undef HAVE_GETTIMEOFDAY
-
 /* Define to 1 if you have the <gssapi/gssapi.h> header file. */
 #undef HAVE_GSSAPI_GSSAPI_H
 

src/include/port.h

@@ -327,11 +327,6 @@ extern FILE *pgwin32_popen(const char *command, const char *type);
 #define popen(a,b) pgwin32_popen(a,b)
 #define pclose(a) _pclose(a)
 
-/* New versions of MingW have gettimeofday, old mingw and msvc don't */
-#ifndef HAVE_GETTIMEOFDAY
-/* Last parameter not used */
-extern int	gettimeofday(struct timeval *tp, struct timezone *tzp);
-#endif
 #else							/* !WIN32 */
 
 /*

src/include/port/win32_port.h

@@ -179,16 +179,11 @@
 #define SIGUSR1				30
 #define SIGUSR2				31
 
-/*
- * New versions of MinGW have gettimeofday() and also declare
- * struct timezone to support it.
- */
-#ifndef HAVE_GETTIMEOFDAY
-struct timezone
-{
-	int			tz_minuteswest; /* Minutes west of GMT.  */
-	int			tz_dsttime;		/* Nonzero if DST is ever in effect.  */
-};
+/* MinW has gettimeofday(), but MSVC doesn't */
+#ifdef _MSC_VER
+struct timezone;
+/* Last parameter not used */
+extern int	gettimeofday(struct timeval *tp, struct timezone *tzp);
 #endif
 
 /* for setitimer in backend/port/win32/timer.c */

src/port/win32gettimeofday.c

@@ -1,8 +1,8 @@
 /*
- * gettimeofday.c
+ * win32gettimeofday.c
  *	  Win32 gettimeofday() replacement
  *
- * src/port/gettimeofday.c
+ * src/port/win32gettimeofday.c
  *
  * Copyright (c) 2003 SRA, Inc.
  * Copyright (c) 2003 SKC, Inc.

src/tools/msvc/Mkvcbuild.pm

@@ -101,7 +101,7 @@ sub mkvcbuild
 	our @pgportfiles = qw(
 	  chklocale.c explicit_bzero.c
 	  getpeereid.c getrusage.c inet_aton.c
-	  getaddrinfo.c gettimeofday.c inet_net_ntop.c kill.c open.c
+	  getaddrinfo.c inet_net_ntop.c kill.c open.c
 	  snprintf.c strlcat.c strlcpy.c dirmod.c noblock.c path.c
 	  dirent.c getopt.c getopt_long.c
 	  preadv.c pwritev.c pg_bitutils.c
@@ -111,6 +111,7 @@ sub mkvcbuild
 	  win32dlopen.c
 	  win32env.c win32error.c
 	  win32fdatasync.c
+	  win32gettimeofday.c
 	  win32link.c
 	  win32pread.c
 	  win32pwrite.c

src/tools/msvc/Solution.pm

@@ -220,7 +220,6 @@ sub GenerateFiles
 		ENABLE_GSS                 => $self->{options}->{gss} ? 1 : undef,
 		ENABLE_NLS                 => $self->{options}->{nls} ? 1 : undef,
 		ENABLE_THREAD_SAFETY       => 1,
-		GETTIMEOFDAY_1ARG          => undef,
 		HAVE_APPEND_HISTORY        => undef,
 		HAVE_ASN1_STRING_GET0_DATA => undef,
 		HAVE_ATOMICS               => 1,
@@ -267,7 +266,6 @@ sub GenerateFiles
 		HAVE_GETOPT_LONG                            => undef,
 		HAVE_GETPEEREID                             => undef,
 		HAVE_GETPEERUCRED                           => undef,
-		HAVE_GETTIMEOFDAY                           => undef,
 		HAVE_GSSAPI_GSSAPI_H                        => undef,
 		HAVE_GSSAPI_H                               => undef,
 		HAVE_HMAC_CTX_FREE                          => undef,