MFC r198335,198365: remove dependency between NO_WARNS and CSTD

There is no reason to have it.

Reviewed by:	dim
MFC slackers:	rdivacky, ru
MFC r253604: rename scheduler->swapper and SI_SUB_RUN_SCHEDULER->SI_SUB_LAST
MFC r253603: zfs: move vnode creation from zfs_znode_cache_constructor
to zfs_znode_alloc
MFC r253606: zfs module: perform cleanup during shutdown in addition to
module unload
MFC r253772,253773,253989: dtrace disassembler: take the latest/last
CDDL code from OpenSolaris
MFC r253996,253997: opensolaris code: translate INVARIANTS to DEBUG and
ZFS_DEBUG

Please note that support for compiling ZFS into a kernel is not in this
branch as of now.
Also, not all modules from head are in this branch.
MFC r253677,253679: make path matching in devfs rules consistent and
sane (and safer)
MFC r212966: Modify devfs_fqpn() for future use in devfs path reference
counting code

This should fix build failure introduced in r254708.

Pointyhat to:	avg
MFC slacker:	jh
MFC r254438:
Fix some USB controller names according to pciconf output.

Submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC r250412: posix_spawn_file_actions_addopen(3): Correct error for bad file
descriptor.

As per POSIX.1-2008, posix_spawn_file_actions_add* return [EBADF] if a file
descriptor is negative, not [EINVAL]. The bug was only in the manual page;
the code is correct.
MFC 250421: posix_spawn_file_actions_adddup2(3): Document difference with
dup2().

The ability to clear a file descriptor's close-on-exec flag via
posix_spawn_file_actions_adddup2() is in fact proposed in Austin Group issue
#411.