Fix up for inc/ufs.h.

Add return.c external functions to inc/return.h (previously only macros) and update
    makefile-tail and relevant files.

	modified:   makefile-tail
	modified:   ../inc/return.h
	new file:   ../inc/ufs.h
	modified:   ../src/bbtsub.c
	modified:   ../src/dir.c
	modified:   ../src/dsk.c
	modified:   ../src/intcall.c
	modified:   ../src/subr.c
	modified:   ../src/ufs.c
	modified:   ../src/vmemsave.c
	modified:   ../src/xc.c

src/vmemsave.c

@@ -77,6 +77,7 @@ static char *id = "$Id: vmemsave.c,v 1.2 1999/01/03 02:07:45 sybalsky Exp $ Copy
 #include "dbprint.h"
 #include "devif.h"
 #include "dsk.h"
+#include "ufs.h"
 #include "dir.h"
 
 #ifdef GCC386