qcl: 0.6.3: a language for quantum computers

Wikipedia lists QCL as one of the first quantum programming languages. This formula downloads and installs the latest version of QCL from the maintainer's website. In addition, the formula copies the standard QCL library so that the interpreter is able to run properly.

I have simplified this as suggested.

Now using ENV.cxx and parametrized system arguments

Added cause to fails_with