patch 8.1.1115: cannot build with older C compiler

Problem:    Cannot build with older C compiler.
Solution:   Move variable declaration to start of block.
diff --git a/src/autocmd.c b/src/autocmd.c
index 9a758c8..aa11143 100644
--- a/src/autocmd.c
+++ b/src/autocmd.c
@@ -391,10 +391,10 @@
 	prev_ap = &(first_autopat[(int)event]);
 	for (ap = *prev_ap; ap != NULL; ap = *prev_ap)
 	{
-	    // loop over all commands for this pattern
-	    prev_ac = &(ap->cmds);
 	    int has_cmd = FALSE;
 
+	    // loop over all commands for this pattern
+	    prev_ac = &(ap->cmds);
 	    for (ac = *prev_ac; ac != NULL; ac = *prev_ac)
 	    {
 		// remove the command if the pattern is to be deleted or when
@@ -405,17 +405,17 @@
 		    vim_free(ac->cmd);
 		    vim_free(ac);
 		}
-		else {
+		else
+		{
 		    has_cmd = TRUE;
 		    prev_ac = &(ac->next);
 		}
 	    }
 
-	    if (ap->pat != NULL && !has_cmd) {
+	    if (ap->pat != NULL && !has_cmd)
 		// Pattern was not marked for deletion, but all of its
 		// commands were.  So mark the pattern for deletion.
 		au_remove_pat(ap);
-	    }
 
 	    // remove the pattern if it has been marked for deletion
 	    if (ap->pat == NULL)