Refactor enmasse() and recurse() to reflect depth

The HLP-changes to sbase have been a great addition of functionality,
but they kind of "polluted" the enmasse() and recurse() prototypes.
As this will come in handy in the future, knowing at which "depth"
you are inside a recursing function is an important functionality.

Instead of having a special HLP-flag passed to enmasse, each sub-
function needs to provide it on its own and can calculate results
based on the current depth (for instance, 'H' implies 'P' at
depth > 0).
A special case is recurse(), because it actually depends on the
follow-type. A new flag "recurse_follow" brings consistency into
what used to be spread across different naming conventions (fflag,
HLP_flag, ...).

This also fixes numerous bugs with the behaviour of HLP in the
tools using it.

libutil/fnck.c

@@ -5,7 +5,7 @@
 
 void
 fnck(const char *a, const char *b,
-     int (*fn)(const char *, const char *, char), char ff)
+     int (*fn)(const char *, const char *, int), int depth)
 {
 	struct stat sta, stb;
 
@@ -16,6 +16,6 @@ fnck(const char *a, const char *b,
 		eprintf("%s -> %s: same file\n", a, b);
 	}
 
-	if (fn(a, b, ff) < 0)
+	if (fn(a, b, depth) < 0)
 		eprintf("%s -> %s:", a, b);
 }