patch 9.1.1182: No cmdline completion for 'completefuzzycollect'

Problem:  No cmdline completion for the 'completefuzzycollect' option
          (after v9.1.1178)
Solution: Add cmdline completion for the 'completefuzzycollect' option,
          improve its description in optwin.vim (zeertzjq).

closes: #16813

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/optiondefs.h b/src/optiondefs.h
index a8d7972..38e871c 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -656,7 +656,7 @@
 #endif
 			    SCTX_INIT},
     {"completefuzzycollect", "cfc", P_STRING|P_VI_DEF|P_ONECOMMA|P_NODUP,
-			    (char_u *)&p_cfc, PV_NONE, did_set_completefuzzycollect, NULL,
+			    (char_u *)&p_cfc, PV_NONE, did_set_completefuzzycollect, expand_set_completefuzzycollect,
 			    {(char_u *)"", (char_u *)0L}
 			    SCTX_INIT},
     {"completeitemalign", "cia", P_STRING|P_VI_DEF|P_ONECOMMA|P_NODUP,