patch 9.0.2110: [security]: overflow in ex address parsing

Problem:  [security]: overflow in ex address parsing
Solution: Verify that lnum is positive, before substracting from
          LONG_MAX

[security]: overflow in ex address parsing

When parsing relative ex addresses one may unintentionally cause an
overflow (because LONG_MAX - lnum will overflow for negative addresses).

So verify that lnum is actually positive before doing the overflow
check.

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2110,
 /**/
     2109,
 /**/