'RELENG_7_0_0_RELEASE'.

This commit was manufactured to restore the state of the 7.0-RELEASE image.

call the pad-less versions of the corresponding syscalls if the running
kernel supports it.  Check kern.osreldate once per program and cache the
result to select the appropriate syscall.  This maintains userland
compatability with kernel.old's from quite a while back.

Approved by:  re (kensmith)

The thread jump table has been resorted, so you need to
keep libc, libpthread, and libthr in sync.

Submitted by:	xu

  * Add posix_memalign().

  * Move calloc() from calloc.c to malloc.c.  Add a calloc() implementation in
    rtld-elf in order to make the loader happy (even though calloc() isn't
    used in rtld-elf).

  * Add _malloc_prefork() and _malloc_postfork(), and use them instead of
    directly manipulating __malloc_lock.

Approved by:	phk, markm (mentor)

stdio/ and stdlib/.  Don't define __cleanup twice.

struct _spinlock.  Keep the typedef in for now; another set of changes
may come around to clean up consumers of spinlocks.

Requested by:	bde

it around an application's fork() call.  Our new thread libraries
(libthr, libpthread) can now have threads running while another
thread calls fork().  In this case, it is possible for malloc
to be left in an inconsistent state in the child.  Our thread
libraries, libpthread in particular, need to use malloc internally
after a fork (in the child).

Reviewed by:	davidxu

`implicit declaration of function' variety.