MFC: r262571

Add missing includes and remove two unused ones.

Reviewed by:	loos
MFC various fixes for the ATF tests.

- r260505 Allow tests to provide a Kyuafile when they relied on auto-generation.
- r260525 Respect the original layout of the atf-{c,c++} tests.
- r260526 Fix path to the process_helpers for the libatf-c++ tests.
- r260576 Generate and install pkg-config files for atf.
- r260577 Add atf pkg-config files from the vendor branch.
- r260584 Prevent misc_helpers from running as a test.