Changes

ls: Make -, apply to -s as well as -l.

While here, remove a bogus comment about a gcc bug.  The bug was in ls,
which used an incorrect format string, and in libc, which accepted it.

MFC after:	1 week
Reviewed by:	brooks
Differential Revision:	https://reviews.freebsd.org/D46067

pax: Clear arcn in each read function.

Instead of initializing individual fields to zero, clear the entire
struct prior to populating it.

MFC after:	1 week
Sponsored by:	Klara, Inc.
Reviewed by:	0mp, markj
Differential Revision:	https://reviews.freebsd.org/D46097

malloc: Handle large malloc sizes in malloc_size()

Reviewed by:	kib, emaste
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D45661

dtrace: Avoid including dtrace_isa.c directly into dtrace.c

This was done in the original DTrace import, presumably because that
made it a bit easier to handle includes.  However, this can cause
dtrace_getpcstack() to be inlined into dtrace_probe(), resulting in a
missing frame in stack traces since dtrace_getpcstack() takes care to
bump "aframes" to account for its own stack frame.

To avoid this, compile dtrace_isa.c separately on all platforms.  Add
requisite includes.

MFC after:	2 weeks
Sponsored by:	Innovate UK