ms/uplink-x86.pl: close the file handle that was opened

Fixes #5656
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6079)

ms/uplink-x86.pl

@@ -41,4 +41,4 @@ for ($i=1;$i<=$N;$i++) {
 }
 &asm_finish();
 
-close OUTPUT;
+close STDOUT;