Add missing Forward declarations for rename_area and remove_area and fix a call-site.

Upstream issue tracked here:

https://sourceforge.net/p/slashem/bugs/963/

https://fedoraproject.org/wiki/Toolchain/PortingToModernC

diff --git a/include/extern.h b/include/extern.h

index 8a839db..55a9829 100644

--- a/include/extern.h

+++ b/include/extern.h

@@ -2274,6 +2274,8 @@ E FILE *FDECL(freopen_area, (const char *,const char *,const char *, FILE *));

 E int FDECL(chmod_area, (const char *, const char *, int));

 E int FDECL(open_area, (const char *, const char *, int, int));

 E int FDECL(creat_area, (const char *, const char *, int));

+E int FDECL(rename_area, (const char *,const char *,const char *));

+E int FDECL(remove_area, (const char *,const char *));

 E boolean FDECL(lock_file_area, (const char *, const char *,int));

 E void FDECL(unlock_file_area, (const char *, const char *));

 #endif

diff --git a/src/files.c b/src/files.c

index 469a23f..09738c8 100644

--- a/src/files.c

+++ b/src/files.c

@@ -566,7 +566,7 @@ int lev;

 	if (lev == 0 || (level_info[lev].flags & LFILE_EXISTS)) {

 		set_levelfile_name(lock, lev);

 #ifdef FILE_AREAS

-		(void) remove_area(FILE_AREA_LEVL, lock, 0);

+		(void) remove_area(FILE_AREA_LEVL, lock);

 #else

 # ifdef HOLD_LOCKFILE_OPEN

 		if (lev == 0) really_close();