(bzero, bcopy): Obsolete BSDisms; remove. Remove some calls without

effect.  Replace calls by struct assignment where possible.  Replace
clear buffer, copy string to buffer by strncpy().  Use assignment to
clear when that's clearer.  Replace overlapping copy through bounce
buffer by memmove().  Replace rest by standard memset() and memcpy().
Also use sizeof() instead of literal array sizes for robustness, and
instead of symbolic array sizes for clarity.

src/lib/as/as_cache.c

@@ -166,7 +166,7 @@ as_clear_cachepath()
     }
     /* Note we don't free the fromhead here, we just zero it.  That way,
        we can use it next time without mallocing int */
-    bzero((s_char *)fromhead, (sizeof(struct as_frompath *) * WORLD_Y));
+    memset(fromhead, 0, (sizeof(struct as_frompath *) * WORLD_Y));
 }
 
 struct as_path *