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

Restore the ABI of 'struct fpreg' on powerpc.

The PT_{GET,SET}FPREGS requests use 'struct fpreg' and the NT_FPREGSET
core note stores a copy of 'struct fpreg'. As with x86 and the floating
point state there compared to the extended state in XSAVE, struct fpreg
on powerpc now only holds the 'base' FP state, and setting it via
PT_SETFPREGS leaves the extended vector state in a thread unchanged.

Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D5004

Resolve warnings exposed by LINT.
o Put prototypes in a single header only.
o Fix printf format specifiers.

Add a floating-point emulator so that a single userland or single ABI
can run on processors that don't have a FPU. This is typically the
case for Book E processors. While a tuned system will probably want
to use soft-float (or use a processor that has a FPU if the usage is
FP intensive enough), allowing hard-float on FPU-less systems gives
great portability and flexibility.

Obtained from: NetBSD