Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

tests: Add ATF_REQUIRE_SYSCTL_BOOL

Modify a capability mode test to use it for kern.trap_enotcap, to avoid
false positives.

MFC after: 1 week
Sponsored by: The FreeBSD Foundation

Fix sys/opencrypto/blake2_test when kern.cryptodevallowsoft=0

Two of these testcases require software crypto to be enabled. Curiously, it
isn't by default.

PR: 230671
Reported by: Jenkins
Reviewed by: cem
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D16755

Add ATF_REQUIRE_FEATURE and PLAIN_REQUIRE_FEATURE macros for
testing for kernel features via the feature_present(3) libcall

The semantics are similar to the other macros in the header (skip
testcase with ATF macro; exit with appropriate exit code with the
PLAIN macro)

MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division

Fix typo. It should have been atf_tc_skip, not atf_skip

Reported by: many, Jenkins
Pointyhat to: ngie
MFC after: 4 days

ATF_REQUIRE_KERNEL_MODULE: use atf_skip, not ATF_REQUIRE_MSG so the testcase
no longer bombs out
PLAIN_REQUIRE_KERNEL_MODULE: use printf + _exit, no err so the testcase no
longer bombs out if it prints to stderr

MFC after: 5 days

Add initial (unpolished) macros for interfacing with the FreeBSD test suite

This is very rough, but will be replaced/redesigned some time soon after I fix
the Jenkins breakage I introduced

MFC after: 6 days