patch 8.2.3297: cannot use all commands inside a {} block

Problem:    Cannot use all commands inside a {} block after :command and
            :autocmd.
Solution:   Do consider \n to separate commands. (closes #8620)

src/ex_eval.c

@@ -1461,6 +1461,18 @@ ex_endblock(exarg_T *eap)
 	leave_block(cstack);
 }
 
+    int
+inside_block(exarg_T *eap)
+{
+    cstack_T	*cstack = eap->cstack;
+    int		i;
+
+    for (i = 0; i <= cstack->cs_idx; ++i)
+	if (cstack->cs_flags[cstack->cs_idx] & CSF_BLOCK)
+	    return TRUE;
+    return FALSE;
+}
+
 /*
  * ":throw expr"
  */