patch 9.0.1226: spurious empty line when using text properties

Problem:    Spurious empty line when using text propertie and virtual text.
Solution:   Do not set "text_prop_follows" when the other text property is not
            virtual text. (closes #11846)
diff --git a/src/drawline.c b/src/drawline.c
index a82a5e4..b4208a8 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -2016,7 +2016,8 @@
 			    text_prop_type = pt;
 			    text_prop_attr =
 				   hl_combine_attr(text_prop_attr, used_attr);
-			    other_tpi = used_tpi;
+			    if (used_tpi >= 0 && text_props[used_tpi].tp_id < 0)
+				other_tpi = used_tpi;
 			    text_prop_flags = pt->pt_flags;
 			    text_prop_id = tp->tp_id;
 			    used_tpi = tpi;