patch 8.0.0837: signs can be drawn on top of console messages

Problem:    Signs can be drawn on top of console messages.
Solution:   don't redraw at a prompt or when scrolled up. (Christian Brabandt,
            closes #1907)
diff --git a/src/version.c b/src/version.c
index 3aab4d3..d6f08bb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    837,
+/**/
     836,
 /**/
     835,