Revert fsync ifdef behaviour and name, now default variant acts like

original one.
Suggested by: peter

libexec/mail.local/Makefile

@@ -2,7 +2,9 @@
 
 PROG=	mail.local
 MAN8=	mail.local.8
-# CFLAGS+= -DEXTRA_SAFETY
+.if defined(DONT_FSYNC)
+CFLAGS+= -DDONT_FSYNC
+.endif
 BINOWN=	root
 BINMODE=4555
 INSTALLFLAGS=-fschg

libexec/mail.local/mail.local.c

@@ -298,7 +298,7 @@ err1:		(void)close(mbfd);
 		return;
 	}
 
-#ifdef EXTRA_SAFETY
+#ifndef DONT_FSYNC
 	/* Flush to disk, don't wait for update. */
 	if (fsync(mbfd)) {
 		e_to_sys(errno);