patch 8.2.4093: cached breakindent values not initialized properly

Problem:    Cached breakindent values not initialized properly.
Solution:   Initialize and cache formatlistpat. (Christian Brabandt,
            closes #9526, closes #9512)
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index c7fbde6..65ed54f 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1370,6 +1370,7 @@
 			    text should normally be narrower. This prevents
 			    text indented almost to the right window border
 			    occupying lot of vertical space when broken.
+			    (default: 20)
 		shift:{n}   After applying 'breakindent', the wrapped line's
 			    beginning will be shifted by the given number of
 			    characters.  It permits dynamic French paragraph