patch 8.1.1509: cmdline_row can become negative, causing a crash

Problem:    Cmdline_row can become negative, causing a crash.
Solution:   Make sure cmdline_row does not become negagive. (closes #4102)

Author: brammool

src/misc1.c

@@ -1447,9 +1447,9 @@ prompt_for_number(int *mouse_used)
     i = get_number(TRUE, mouse_used);
     if (KeyTyped)
     {
-	/* don't call wait_return() now */
-	/* msg_putchar('\n'); */
-	cmdline_row = msg_row - 1;
+	// don't call wait_return() now
+	if (msg_row > 0)
+	    cmdline_row = msg_row - 1;
 	need_wait_return = FALSE;
 	msg_didany = FALSE;
 	msg_didout = FALSE;

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1509,
 /**/
     1508,
 /**/