patch 9.0.0518: virtual text highlight starts too early with 'nowrap'

Problem:    Virtual text highlight starts too early with 'nowrap' and 'number'
            set.
Solution:   Add the offset to the attribute skip count. (issue #11138)
diff --git a/src/version.c b/src/version.c
index 684f959..05dc50c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    518,
+/**/
     517,
 /**/
     516,