ISPN-4118 Unreliable test: ThreadLocalLeakTest.testCheckThreadLocalLeaks

Ignore the CounterHashCode thread local in EquivalentConcurrentHashMapV8,
it should not be considered a leak since it is static.
ISPN-3787 Upgrade to c3p0 0.9.5-pre4
ISPN-4369 Upgrade H2 driver to 1.3.173
ISPN-4118 Allow leaking the threadlocal from the embedded JDK8 CHM