Bug fix: Avoid ext:system on ECL
ext:system is a wrapper around ext:run-program that forces :output nil, which is not something we want. See also https://bugs.launchpad.net/asdf/+bug/1638870
ext:system is a wrapper around ext:run-program that forces :output nil, which is not something we want. See also https://bugs.launchpad.net/asdf/+bug/1638870