Check if another LP64 BLAS is loaded

[ViralBShah]

From JuliaSmoothOptimizers/MUMPS.jl#123 (comment)

@amontoison - If another LP64 BLAS/LAPACK is loaded, and I load this one, wouldn't I expect to overwrite the old one? Maybe there should be a force = true kind of argument.

[amontoison]

If OpenBLAS32.jl is used as a standalone package like MKL.jl or AppleAccelerate.jl, then you can expect it to overwrite the old LP64 BLAS / LAPACK.

However, I'm concerned that if OpenBLAS32.jl is used as a dependency of packages with artifacts compiled with LBT, by doing using MyPackage, you indirectly invoke using OpenBLAS32, which overwrites the BLAS / LAPACK backend.