JAVA_HOME is not set properly on Linux

[dsavenko]

Hi,

ck detect soft:compiler.java may not set JAVA_HOME properly. It searches for javac and may find a symlink /usr/lib/javac. If this option is chosen, JAVA_HOME is set to /usr. In fact, it should be set to something like /usr/lib/jvm/java-8-openjdk-amd64.

One way to fix it is to search for rt.jar instead of javac. It's not symlinked anywhere.

But, I guess, the best way would be to add symlink detection/resolution, so that symlinks are not considered at all.