patch 9.0.2032: cannot get mouse click pos for tab or virt text

Problem:  Cannot accurately get mouse clicking position when clicking on
          a TAB or with virtual text.
Solution: Add a "coladd" field to getmousepos() result.

closes: #13335

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
diff --git a/src/move.c b/src/move.c
index 72490d2..bb65024 100644
--- a/src/move.c
+++ b/src/move.c
@@ -1547,7 +1547,7 @@
     static int
 virtcol2col(win_T *wp, linenr_T lnum, int vcol)
 {
-    int		offset = vcol2col(wp, lnum, vcol - 1);
+    int		offset = vcol2col(wp, lnum, vcol - 1, NULL);
     char_u	*line = ml_get_buf(wp->w_buffer, lnum, FALSE);
     char_u	*p = line + offset;