patch 9.0.1839: No Makefile rule to build cscope database

Problem:  No Makefile rule to build cscope database
Solution: Add rule

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 512950a..5f6995c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1839,
+/**/
     1838,
 /**/
     1837,