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

Introduce a new proc service routine ps_linfo() to get LWP info.

Add support for XMM registers in GDB for x86 processors that support
SSE (or its successors).

Reviewed by: marcel, davidxu
MFC After: 2 weeks

Re-implement this file, including copyright notice. Keep David Xu as
copyright owner. Typical bugs fixed by this are:
o various style(9) bugs,
o #ifdef'd out code,
o lack of comments,
o missing const,
o introduction of obsolete functions,
o missing __BEGIN_DECLS & __END_DECLS,

The major flaw in this version, that was also present in the previous
version is the lack of man page. Minor flaws undoubtedly still exist.

Add proc_service.h, the common file both debugger and libthread_db will
use, program wants to load libthread_db.so should provid proc service
interface.