add gmvolf toolchain definition
add unit test for cgoolf toolchain + required test modules
Revert "add gmvolf toolchain definition", gmvolf support was already added in develop via https://github.com/hpcugent/easybuild-framework/pull/585

This reverts commit 0b99ad0a43275f0a432db62b03e8c8c2fe1f618f.
Merge pull request #1 from boegel/clang-toolchains

Add cgoolf unit test