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

ulimit(3): simplify.

rlim_t is at least as large as long, so we don't need the
extra variable to keep the intermediate step. We don't
need the volatile either.

The code was tested on i386 and amd64.

Suggested by: bde
X-MFC with: r278803

ulimit(3): Fix broken check.

The existing implementation had a broken comparison that could
overflow and return confusing values. Replace this with a check
that avoids the overflow before it happens.

Consistently return a maximum value also on the case of negative
arguments since negative is considered an overflow and means
infinity for our current setrlimit().

New revamped version is credited to Bruce Evans.

CID: 1199295
MFC after: 1 week

Revert 278634: This broke the build due to the compiler being too clever.

Will be back, with proper compiler workarounds.

ulimit(3): Fix broken check.

The existing implementation had a broken comparison that could overflow.
Replace this with a check that avoids the overflow before it happens.

Consistently return a maximum value also on the case of negative
arguments since negative is considered an overflow and means
infinity for our current setrlimit().

Discussed with: bde (rather extensively)

CID: 1199295
MFC after: 1 week

Rename UL_GETSIZE to UL_GETFSIZE and UL_SETSIZE to UL_SETFSIZE; these are
the names required by 1003.1-2001. The old names are retained for
source compatibility with FreeBSD 5.0 and will be removed before 6.0.

Remove unused variable: size.

Implement POSIX.1-2001 (XSI)'s ulimit(3).

Submitted by: Kyle Martin <mkm@ieee.org>