the execute bit off for files, but keep search permission for directories.
Change contributed in PR kern/21538 by Pavel Arnost, based on some FreeBSD
patches.
Further manpage changes, and backward-compatibility adjustments done by me.
Also fixes PR kern/16778 by Johan Danielsson, and PR kern/3400 by Rick Byers
malloc types into a structure, a pointer to which is passed around,
instead of an int constant. Allow the limit to be adjusted when the
malloc type is defined, or with a function call, as suggested by
Jonathan Stone.