Make JDK byte code verification bug workaround Java 8 compatible

A workaround for a JDK bug that affects PowerMock only work with Java 7.
The -UseSplitVerifier option is no longer supported in Java 8. As an
alternative workaround, this patch disables the byte code verifier
entirely. Since this is only used with our own unit tests, the impact
is low.

Target: trunk
Request: 2.10
Request: 2.9
Request: 2.8
Request: 2.7
Request: 2.6
Require-notes: no
Requier-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7197/
(cherry picked from commit d06ed79d0bd6f1e387fcd10ae3a62b32895d0d35)