When building with multiple parallel jobs, it can be hard to track down the actual error causing the build to fail.

This patch addresses this in two parts. Firstly, it tries to locate a sequence of failing make targets, where the first is the initial failing target, which is usually very specific, and repeats these at the end of the build. (This will work only on GNU Make 4)

Secondly, if the failure occured during compilation or linking, the actual output of the failing compilation/link command is repeated. Since the most likely build failure a common developer will encounter are compilation or link failures, this will hopefully help to make most build errors quick to resolve. (This will unfortunately not work for hotspot code until the new Hotspot build system is integrated.)