Reapply whitespace style changes from r346443 after recent changes to tests/sys/opencrypto

From r346443:
"""
Replace hard tabs with four-character indentations, per PEP8.

This is being done to separate stylistic changes from the tests from functional
ones, as I accidentally introduced a bug to the tests when I used four-space
indentation locally.

No functional change.
"""

MFC after: 2 months
Discussed with: jhb