Simply call org.apache.jasper.JspC, then exit.
As of Tomcat 8.5.33, forking their JspC won't complete,
because the JspC compilation is now threaded and the thread pool workers aren't daemons.
Will fixed in a 8.5.35, but we don't know what version distros may have.
Additionally, if the system property build.reproducible is "true",
attempts to generate a reproducible build by compiling the
jsps in order, for a consistent web.xml file.
We could set fork=false in build.xml, but then the paths are all wrong.
Only for use in build scripts, obviously not a public API.
See apps/routerconsole/java/build.xml for more information.