Update javac to work with modular image

This task tracks updating javac to work with a modular image.

Today, then javac uses the value of the sun.boot.class.path and java.ext.dirs properties when compiling against the boot and extension directory. This works for directories and JAR files. A solution will be required when the platform classes linked into a special format in the modular image.

Need to have support for replacement command line options to replace bootclasspath options.