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

ARM: Remove trailing whitespace from sys/arm/include
No functional changes.

Approved by: kib (mentor)

trim trailing whitespace

Whitespace nit.

In __bswap16_var(), make sure the 16 upper bits are cleared; while
optimizing, gcc4 doesn't always do so.

Reported by: Nathan Whitehorn
Approved by: re (blanket)

Use a + constraint modifier for a register arg in __bswap16_var().

Reviewed by: cognet

Asm version of bswap16().

Obtained from: NetBSD

Start to support the big endian case as well.

Start all license statements with /*-

Use casts to enforce the return type of bswap16() and bswap32().

Add optimized version of the bswap macroes for constants if __OPTIMIZED__ is
defined.

*blush*
Fix htonl and htons.

Add some endianess-related functions and macros.

Style sync.

StrongARM platform-specific definitions.