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

libc: do not include <sys/types.h> where <sys/param.h> was already included

According to style(9):
> normally, include <sys/types.h> OR <sys/param.h>, but not both.
(<sys/param.h> already includes <sys/types.h> when LOCORE is not defined).

Clean r268867.

Proposed by: bde

Use unsigned optlen in getsourcefilter()

Sizes can not be negative and the functions that use it
expect an unsigned value anyways.

Obtained from: Apple (Libc-997.90.3)
MFC after: 1 week

Use the LLINDEX macro to access the link-level I/F index. This makes
it possible to work with a different type for the sdl_index field --
it only requires a recompile.

Obtained from: Juniper Networks, Inc.

Fix an obvious bug in getsourcefilter()'s use of struct __msfilterreq;
the kernel will return in msfr_nsrcs the number of source filters
in-mode for a given multicast group.
However, the filters themselves were never copied out, as the libc
function clobbers this field with zero, causing the kernel to assume
the provided vector of struct sockaddr_storage has zero length.
This bug would only affect users of SSM multicast, which is shimmed
in 7.x.
Picked up during mtest(8) refactoring.

MFC after: 1 day

Update copyright.

Fix missing prototype warnings. (Compile errors with -Werror on)
When using namespace.h/un-namespace.h, you use _ versions of syscalls.
Change getsockopt() to _getsockopt() and same for setsockopt().

Approved by: re

Fix a typo which crept in from an earlier version of this file.

Add missing userland support files from previous commit for the new
multicast source filter API functions.