Implement an optional method using sigstop/sigcont instead of sigkill

make, ninja and therefore package managers like Gentoo's portage allow to run compilation jobs in parallel. Sometimes, if a few jobs simultaneously require very large amounts of memory (as gcc with lto or qtwebengine regularily do) , the swapper starts trashing pages, prolonging the installation of such a package from hours to days and equally impeding user interaction . Killing an offending task would be pointless in such a situation, whereas manually stopping each of such tasks and allowing to continue e.g. only one of them at a time until the memory pressure subsides does work very well.