Remove configure probe for sys/select.h.

<sys/select.h> is in SUSv3 and every targeted Unix system has it.
Provide an empty header in src/include/port/win32 so that we can
include it unguarded even on Windows.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CA%2BhUKG%2BL_3brvh%3D8e0BW_VfX9h7MtwgN%3DnFHP5o7X2oZucY9dg%40mail.gmail.com

configure

@@ -13874,7 +13874,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
 fi
 
 
-for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h langinfo.h mbarrier.h net/if.h netinet/tcp.h sys/epoll.h sys/event.h sys/ipc.h sys/personality.h sys/prctl.h sys/procctl.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/signalfd.h sys/sockio.h sys/ucred.h termios.h ucred.h
+for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h langinfo.h mbarrier.h net/if.h netinet/tcp.h sys/epoll.h sys/event.h sys/ipc.h sys/personality.h sys/prctl.h sys/procctl.h sys/resource.h sys/sem.h sys/shm.h sys/signalfd.h sys/sockio.h sys/ucred.h termios.h ucred.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"

configure.ac

@@ -1461,7 +1461,6 @@ AC_CHECK_HEADERS(m4_normalize([
 	sys/prctl.h
 	sys/procctl.h
 	sys/resource.h
-	sys/select.h
 	sys/sem.h
 	sys/shm.h
 	sys/signalfd.h

doc/src/sgml/libpq.sgml

@@ -9211,11 +9211,9 @@ main(int argc, char **argv)
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
+#include <sys/select.h>
 #include <sys/time.h>
 #include <sys/types.h>
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "libpq-fe.h"
 

src/backend/libpq/auth.c

@@ -16,13 +16,11 @@
 #include "postgres.h"
 
 #include <sys/param.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <pwd.h>
 #include <unistd.h>
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "commands/user.h"
 #include "common/ip.h"

src/backend/postmaster/postmaster.c

@@ -70,6 +70,7 @@
 #include <time.h>
 #include <sys/wait.h>
 #include <ctype.h>
+#include <sys/select.h>
 #include <sys/stat.h>
 #include <sys/socket.h>
 #include <fcntl.h>
@@ -77,10 +78,6 @@
 #include <netdb.h>
 #include <limits.h>
 
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
-
 #ifdef USE_BONJOUR
 #include <dns_sd.h>
 #endif

src/backend/tcop/postgres.c

@@ -23,10 +23,8 @@
 #include <limits.h>
 #include <signal.h>
 #include <unistd.h>
-#include <sys/socket.h>
-#ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
-#endif
+#include <sys/socket.h>
 #ifdef HAVE_SYS_RESOURCE_H
 #include <sys/time.h>
 #include <sys/resource.h>

src/bin/pg_basebackup/pg_basebackup.c

@@ -16,13 +16,11 @@
 #include <unistd.h>
 #include <dirent.h>
 #include <limits.h>
+#include <sys/select.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <signal.h>
 #include <time.h>
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_LIBZ
 #include <zlib.h>
 #endif

src/bin/pg_basebackup/pg_recvlogical.c

@@ -14,11 +14,9 @@
 
 #include <dirent.h>
 #include <limits.h>
+#include <sys/select.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "access/xlog_internal.h"
 #include "common/fe_memutils.h"

src/bin/pg_basebackup/receivelog.c

@@ -14,11 +14,9 @@
 
 #include "postgres_fe.h"
 
+#include <sys/select.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "access/xlog_internal.h"
 #include "common/file_utils.h"

src/bin/pg_dump/parallel.c

@@ -53,14 +53,12 @@
 #include "postgres_fe.h"
 
 #ifndef WIN32
+#include <sys/select.h>
 #include <sys/wait.h>
 #include <signal.h>
 #include <unistd.h>
 #include <fcntl.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "fe_utils/string_utils.h"
 #include "parallel.h"

src/bin/pgbench/pgbench.c

@@ -52,10 +52,8 @@
 #endif
 #else							/* no ppoll(), so use select() */
 #define POLL_USING_SELECT
-#ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
 #endif
-#endif
 
 #include "common/int.h"
 #include "common/logging.h"

src/fe_utils/parallel_slot.c

@@ -18,9 +18,7 @@
 
 #include "postgres_fe.h"
 
-#ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
-#endif
 
 #include "common/logging.h"
 #include "fe_utils/cancel.h"

src/include/pg_config.h.in

@@ -511,9 +511,6 @@
 /* Define to 1 if you have the <sys/resource.h> header file. */
 #undef HAVE_SYS_RESOURCE_H
 
-/* Define to 1 if you have the <sys/select.h> header file. */
-#undef HAVE_SYS_SELECT_H
-
 /* Define to 1 if you have the <sys/sem.h> header file. */
 #undef HAVE_SYS_SEM_H
 

src/include/port/win32/sys/select.h

@@ -0,0 +1,3 @@
+/*
+ * src/include/port/win32/sys/select.h
+ */

src/interfaces/libpq/fe-misc.c

@@ -37,15 +37,13 @@
 #include "win32.h"
 #else
 #include <unistd.h>
+#include <sys/select.h>
 #include <sys/time.h>
 #endif
 
 #ifdef HAVE_POLL_H
 #include <poll.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "libpq-fe.h"
 #include "libpq-int.h"

src/port/pgsleep.c

@@ -13,10 +13,8 @@
 #include "c.h"
 
 #include <unistd.h>
-#include <sys/time.h>
-#ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
-#endif
+#include <sys/time.h>
 
 /*
  * In a Windows backend, we don't use this implementation, but rather

src/test/examples/testlibpq2.c

@@ -32,11 +32,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
+#include <sys/select.h>
 #include <sys/time.h>
 #include <sys/types.h>
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 
 #include "libpq-fe.h"
 

src/test/isolation/isolationtester.c

@@ -7,10 +7,8 @@
 
 #include "postgres_fe.h"
 
-#include <sys/time.h>
-#ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
-#endif
+#include <sys/time.h>
 
 #include "datatype/timestamp.h"
 #include "isolationtester.h"

src/test/modules/libpq_pipeline/libpq_pipeline.c

@@ -15,10 +15,8 @@
 
 #include "postgres_fe.h"
 
-#include <sys/time.h>
-#ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
-#endif
+#include <sys/time.h>
 
 #include "catalog/pg_type_d.h"
 #include "common/fe_memutils.h"

src/tools/msvc/Solution.pm

@@ -366,7 +366,6 @@ sub GenerateFiles
 		HAVE_SYS_PRCTL_H                         => undef,
 		HAVE_SYS_PROCCTL_H                       => undef,
 		HAVE_SYS_RESOURCE_H                      => undef,
-		HAVE_SYS_SELECT_H                        => undef,
 		HAVE_SYS_SEM_H                           => undef,
 		HAVE_SYS_SHM_H                           => undef,
 		HAVE_SYS_SIGNALFD_H                      => undef,