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

Get rid of the CONCAT macro.

Replace the assembler macro WEAK_ALIAS with a new macro WEAK_REFERENCE which
has the same API as __weak_reference(). Give 'x' in SYS.h a more meaningful
name.

Tested on 32- and 64-bit PowerMac.

Reviewed by: bde

Use the macro WEAK_ALIAS. Tested on 32 and 64-bit.

Turn off default generation of userland dot symbols on powerpc64 now that
we have a binutils that supports it. Kernel dot symbols remain on to assist
DDB.

Provide 64-bit PowerPC support in libc.

Obtained from: projects/ppc64