patch 8.0.1809: various typos

Problem:    Various typos.
Solution:   Correct the mistakes, change "cursur" to "cursor". (closes #2887)
diff --git a/src/ui.c b/src/ui.c
index bb03880..05e82e6 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -1971,7 +1971,7 @@
 # endif
 
 # ifdef FEAT_CONCEAL
-    conceal_check_cursur_line();
+    conceal_check_cursor_line();
 # endif
 }