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

Add support for the __aeabi_c*cmp* functions. These are similar to the
existing functions with the exception they use the condition flags to
store the result.

Differential Revision: https://reviews.freebsd.org/D872
Silence from: current@ and numerics@
MFC after: 1 week

Fix the spelling of function.

Reported by: ian@

Add an optimised version of the float and double helper functions. These
are only used on armv6 when the vfp unit is detected. They will also be
available for the upcoming armv6hf platform, however while not used by
default there will need to be defined for any software that calls them
directly.

Add the required __aeabi_* functions to libc.

The floating point functions are here rather than compiler-rt because the
libc softfloat code allows us to set the rounding mode.