patch 9.0.1513: text scrolls unnecessarily when splitting

Problem:    Text scrolls unnecessarily when splitting and 'splitkeep' is not
            "cursor".
Solution:   Avoid resetting w_skipcol. (Luuk van Baal, closes #12334)
diff --git a/src/window.c b/src/window.c
index 244ee37..27b353e 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1453,6 +1453,8 @@
 
     if (*p_spk != 'c')
     {
+	if (*p_spk == 't')
+	    newp->w_skipcol = oldp->w_skipcol;
 	newp->w_botline = oldp->w_botline;
 	newp->w_prev_height = oldp->w_height - WINBAR_HEIGHT(oldp);
 	newp->w_prev_winrow = oldp->w_winrow + 2 * WINBAR_HEIGHT(oldp);
@@ -6860,14 +6862,16 @@
     }
 
     wp->w_height = height;
-    wp->w_skipcol = 0;
     wp->w_redr_status = TRUE;
     win_comp_scroll(wp);
 
     // There is no point in adjusting the scroll position when exiting.  Some
     // values might be invalid.
     if (!exiting && *p_spk == 'c')
+    {
+	wp->w_skipcol = 0;
 	scroll_to_fraction(wp, prev_height);
+    }
 }
 
     void