The sjavac ("smart javac") was an ambitious project. It should parallelize java compilation, create a background daemon process that kept the JVM "hot" with the JITted javac code, define a public api so only noticeable changes in a class caused further dependency compilations, etc etc.

Some of this never came to fruition. Other were implemented differently, as the `depend` plugin. The only thing we're currently using (and have been for the last few years) is the "server" functionality, that is, the ability to keep a single JVM process alive, and reuse the JITted code.

This code does not belong in the jdk.compiler module. It is a buildtool, pure and simple. Let's move it to it's proper place.