[PBCKP-245] mingw: no need to define custom sleep/usleep

Mingw defines usable them.

src/utils/pgut.c

@@ -1061,20 +1061,6 @@ init_cancel_handler(void)
 	SetConsoleCtrlHandler(consoleHandler, TRUE);
 }
 
-int
-sleep(unsigned int seconds)
-{
-	Sleep(seconds * 1000);
-	return 0;
-}
-
-int
-usleep(unsigned int usec)
-{
-	Sleep((usec + 999) / 1000);	/* rounded up */
-	return 0;
-}
-
 #undef select
 static int
 select_win32(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timeval * timeout)

src/utils/pgut.h

@@ -98,9 +98,4 @@ extern char *pgut_str_strip_trailing_filename(const char *filepath, const char *
 extern int wait_for_socket(int sock, struct timeval *timeout);
 extern int wait_for_sockets(int nfds, fd_set *fds, struct timeval *timeout);
 
-#ifdef WIN32
-extern int sleep(unsigned int seconds);
-extern int usleep(unsigned int usec);
-#endif
-
 #endif   /* PGUT_H */