Don't appease clang static analyzer after all and roll back

the free(3) of mntbuf ... again. There's no point in doing
useless extra work when we're about to exit.

See also r240565.

Not reading file history:	uqs

bin/df/df.c

@@ -296,7 +296,6 @@ main(int argc, char *argv[])
 			prtstat(&mntbuf[i], &maxwidths);
 	if (cflag)
 		prtstat(&totalbuf, &maxwidths);
-	free(mntbuf);
 	return (rv);
 }