Revert "Blind attempt at a Cygwin fix"

This reverts commit e9282e9, which blew
up in a pretty spectacular way.  Re-introduce the original code while we
search for a real fix.

Author: alvherre

configure

@@ -13075,12 +13075,6 @@ if test "$PORTNAME" = "cygwin"; then
  ;;
 esac
 
-  case " $LIBOBJS " in
-  *" win32security.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS win32security.$ac_objext"
- ;;
-esac
-
 fi
 
 ac_fn_c_check_decl "$LINENO" "sys_siglist" "ac_cv_have_decl_sys_siglist" "#include <signal.h>

configure.in

@@ -1596,7 +1596,6 @@ fi
 # Cygwin needs only a bit of that
 if test "$PORTNAME" = "cygwin"; then
   AC_LIBOBJ(dirmod)
-  AC_LIBOBJ(win32security)
 fi
 
 AC_CHECK_DECLS([sys_siglist], [], [],

src/bin/pg_ctl/pg_ctl.c

@@ -212,6 +212,15 @@ write_stderr(const char *fmt,...)
 	vfprintf(stderr, fmt, ap);
 #else
 
+/*
+ * On Cygwin, we don't yet have a reliable mechanism to detect when
+ * we're being run as a service, so fall back to the old (and broken)
+ * stderr test.
+ */
+#ifdef __CYGWIN__
+#define	pgwin32_is_service()	(isatty(fileno(stderr)))
+#endif
+
 	/*
 	 * On Win32, we print to stderr if running on a console, or write to
 	 * eventlog if running as a service