patch 9.0.0911: with 'smoothscroll' set mouse click position may be wrong

Problem:    With 'smoothscroll' set mouse click position may be wrong.
Solution:   Adjust computations for w_skipcol. (Yee Cheng Chin, closes #11514)
diff --git a/src/version.c b/src/version.c
index e9b0431..292d022 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    911,
+/**/
     910,
 /**/
     909,