mdoc(7) already uses the mandoc(1) -Ios argument in the footer line

when .Os has no argument, so do the same for man(7) when .TH has less
than four arguments; there is no reason to treat both differently.
Issue found following a question from Thomas Klausner <wiz at NetBSD>.

1 files changed, 3 insertions, 1 deletions

diff --git a/man.c b/man.c
index bc634341..8e8cf725 100644
--- a/man.c
+++ b/man.c
@@ -92,7 +92,8 @@ man_free(struct man *man)
 }
 
 struct man *
-man_alloc(struct roff *roff, struct mparse *parse, int quick)
+man_alloc(struct roff *roff, struct mparse *parse,
+	const char *defos, int quick)
 {
 	struct man	*p;
 
@@ -100,6 +101,7 @@ man_alloc(struct roff *roff, struct mparse *parse, int quick)
 
 	man_hash_init();
 	p->parse = parse;
+	p->defos = defos;
 	p->quick = quick;
 	p->roff = roff;