Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Check l2cap socket initialisation and define L2CAP_SOCKET_CHECKED
This will fix build.

Avoid floating point arithmetic while calculating iquiry length.

Submitted by: Iain Hibbert < plunky -at- rya-online -dot- net >
MFC after: 1 week

Implement low-level Bluetooth HCI API.
This should make it easier to make Linux BlueZ libhci port.

Reviewed by: Iain Hibbert < plunky -at- rya-online -dot- net > of NetBSD
MFC after: 1 week
Inspired by: Linux BlueZ
Inspired by: NetBSD

Add Bluetooth compatibility shims. Inspired by Linux BlueZ and NetBSD.

Discussed with: Iain Hibbert plunky -at- rya-online -dot- net of NetBSD
MFC after: 1 month