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

Remove some OpenSolaris compatibility stuff now that we're doing it a
different way.

Include the Solaris compatibility definions iff _SOLARIS_C_SOURCE is defined.

This header is for Solaris compatibility only (according to David
O'Brien), so add a comment to that effect to remind folks.

Update copyright.

Include elf32.h and elf64.h to be more code compatable with Solaris.

Add this header back, its existance is an SVR4-ELF tradition.
Our ELF hints bits are still a seperate file.

Requested by: jdp