As a stepping stone in the hotspot makefile conversion, it would be nice to break out the build of the serviceability agent separately and convert it into proper modular build-infra makefiles. Enough work in the build-infra forest has already been done to achieve this easily. Doing this conversion has some value on its own by reducing the special cases currently needed for the jdk.hotspot.agent module.

The jdk.hotspot.agent module also contains java source. The current SA java build compiles with the boot jdk javac with -source/-target JDK N-1. The proposed change will enable us to properly build SA with the interim-langtools javac for JDK N, like all the rest of the JDK classes.

There is already a bug filed for reorganizing the source of the SA agent to conform to the Jigsaw style modular source layout: JDK-8067194, so this task will only change makefiles and build the source from its current location.