Make the package loadable in Windows even though it is not usable

[emmt]

@amontoison

The CUTEst.jl package cannot be loaded on Windows and on any 32-bit architectures. I guess this is because the corresponding DLLs are not provided by CUTEst_jll.jl (see here). If CUTEst.jl could be loaded by using CUTEst for any machine, even though not usable, it would make possible for other packages to (weakly) depend on CUTEst.jl and simply avoid using its methods if

Sys.isunix() && Sys.WORD_SIZE ≥ 64

does not hold. There can even be a method provided by CUTEst.jl like:

"""
    CUTEst.is_supported()

yields whether `CUTEst` is fully supported by the machine of the caller.

"""
is_supported() = Sys.isunix() && Sys.WORD_SIZE ≥ 64

to check this.

This would also help to investigate and solve this issue in PRIMA.jl.

[amontoison]

@emmt
I worked on a new version of CUTEst (2.1.0).
We can compile a shared library on all platform now, the library is not anymore "incomplete".
I need to verify a few things before that I generate a new CUTEst_jll.jl but it should be quite soon.

See ralna/CUTEst#50

[amontoison]

Sorry for the delay @emmt, CUTEst.jl will be loadable on Windows with the release 0.13.3.