patch 8.1.1181: tests for mouse clicks are a bit flaky

Problem:    Tests for mouse clicks are a bit flaky when run in an interactive
            terminal.
Solution:   Use "xterm2" instead of "xterm" for 'ttymouse' to avoid spurious
            drag events.

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1181,
 /**/
     1180,
 /**/