add easyconfigs for gimkl 1.5.9 toolchain and HPL with that toolchain

depends on https://github.com/hpcugent/easybuild-framework/pull/987 and https://github.com/hpcugent/easybuild-framework/pull/989
The `dummy` or empty version for a `dummy` toolchain only determines whether the dependencies are loaded at build time. If the build succeeds, they will always be included in the module file.

So, this is not specific to toolchains, but toolchain installations always work even if the dependencies are not loaded, since nothing is being built...