packfile: make `close_pack_revindex()` static

Since its definition in 2f4ba2a867 (packfile: prepare for the existence
of '*.rev' files, 2021-01-25), the only caller of
`close_pack_revindex()` was within packfile.c.

Thus there is no need for this to be exposed via packfile.h, and instead
can remain static within packfile.c's compilation unit. While we're
here, move the function's opening brace onto its own line.

Noticed-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

packfile.c

@@ -324,7 +324,8 @@ void close_pack_index(struct packed_git *p)
 	}
 }
 
-void close_pack_revindex(struct packed_git *p) {
+static void close_pack_revindex(struct packed_git *p)
+{
 	if (!p->revindex_map)
 		return;
 

packfile.h

@@ -90,7 +90,6 @@ uint32_t get_pack_fanout(struct packed_git *p, uint32_t value);
 
 unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, unsigned long *);
 void close_pack_windows(struct packed_git *);
-void close_pack_revindex(struct packed_git *);
 void close_pack(struct packed_git *);
 void close_object_store(struct raw_object_store *o);
 void unuse_pack(struct pack_window **);