devel/arduino18: support jdk11+

Java 8 had a jre/lib/ext directory which does not exist anymore.
Put the jssc-2.8.0.jar in JAVALIBDIR and embed it in arduino18 so we
are sure it is properly on the classpath.

NB: the patch is modified a little bit over the attachment in the
issue. It now uses less local patches than the original patch.

PR: 292242
Approved-by: maintainer timeout