Update capsicum-test to git commit f4d97414d48b8f8356b971ab9f45dc5c70d53c40

This includes various fixes that I submitted recently such as updating the
pdkill() tests for the actual implemented behaviour
(https://github.com/google/capsicum-test/pull/53) and lots of changes to
avoid calling sleep() and replacing it with reliable synchronization
(pull requests 49,51,52,53,54). This should make the testsuite more reliable
when running on Jenkins. Additionally, process status is now retrieved using
libprocstat instead of running ps and parsing the output
(https://github.com/google/capsicum-test/pull/50). This fixes one previously
failing test and speeds up execution.

Overall, this update reduces the total runtime from ~60s to about 4-5 seconds.