patch 8.1.1885: comments in libvterm are inconsistent

Problem:    Comments in libvterm are inconsistent.
Solution:   Use // comments.  Als update the table of combining characters.
diff --git a/src/version.c b/src/version.c
index 85d47c6..2f032e8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1885,
+/**/
     1884,
 /**/
     1883,