output/outobj.c: free the section name on cleanup

It is a completely unimportant memory leak as the process is about to
exit, but it is easy to clean up.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

Author: H. Peter Anvin (Intel)

output/outobj.c

@@ -711,6 +711,7 @@ static void obj_cleanup(void)
             nasm_free(pubtmp->name);
             nasm_free(pubtmp);
         }
+        nasm_free(segtmp->name);
         nasm_free(segtmp->segclass);
         nasm_free(segtmp->overlay);
         nasm_free(segtmp);