MFC r319455,r319456:

r319455:

Fix up TEST_METADATA

• TEST_METADATA.foo should be TEST_METADATA.run_tests: this will unbreak trying to run the tests on a system without python installed in $PATH.
• The tests require root because they load aesni(4) and/or cryptodev(4) if not already loaded.

r319456:

tests/sys/opencrypto/runtests: apply minor polish to test script

• Refactor kld loading/unloading logic:
  • Use a loop instead of an unrolled one.
  • Check for the module being loaded before trying to load it, to reduce noise when loading modules that are already loaded.
  • Don't mute stderr from kldload -- it could be potentially useful to the tester.
  • In the event that the test script was terminated early, it would leave the modules still attached to the system (which is undesirable). Always unload the modules at test end with EXIT/SIGINT/SIGTERM so the system is returned to its former operating state as best possible. Unload the modules in reverse order, in part for consistency and/or dependency reasons.