This commit fixes a minor memory leak for the digest cache file path in
--rotate-digest-cache mode in the replay_cache_init() function. The leak was
caught by valgrind, and a new test was added to the test suite for it. Here
is the valgrind warning:
==29021== 21 bytes in 1 blocks are definitely lost in loss record 2 of 2
==29021== at 0x4C2B3F8: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==29021== by 0x1103AA: replay_cache_init (replay_cache.c:96)
==29021== by 0x10BB8C: main (fwknopd.c:254)
b820bbbe4b