Update to 2.39b
- Move to LLVM 3.9
- Remove TEST_INSTRUMENTATION option and move instrumentation tests to the test stage
- Remove MINIMIZE_CORPUS option: afl-cmin was always installed anyway
- Remove useless pkg-message: afl-cplot prompts you to install gnuplot on its own
Changes: http://lcamtuf.coredump.cx/afl/ChangeLog.txt
Approved by: mat (mentor)
Differential Revision: https://reviews.freebsd.org/D9820