math/scilab: pin to java 8
Does not build with jdk11+.
[javac] /wrkdirs/usr/ports/math/scilab/work/scilab-6.1.1/modules/graphic_objects/src/java/org/scilab/modules/graphic_objects/xmlloader/CSSParser.java:17: error: package javax.annotation does not exist
PR: 272855
Approved-by: no maintainer