patch 8.0.1254: undefined left shift in gethexchrs()

Problem:    Undefined left shift in gethexchrs(). (geeknik)
Solution:   Use unsigned long. (idea by Christian Brabandt, closes #2255)
diff --git a/src/version.c b/src/version.c
index 0595104..7c293ba 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1254,
+/**/
     1253,
 /**/
     1252,