icedtea: Workaround javaws/web plugin start-up error

This is a workaround to avoid the error: "java.io.IOException: RSA premaster
secret error".

In Java Web Start and the Java web plugin, there seems to be a Java policy
that prevents untrusted code from being loaded, and (probably for security
reasons) it doesn't like the files in the JDK's lib/icedtea/jre/lib/ext
directory to be symlinks.

Worked around it by copying those files instead of symlinking them.