Support for BLAS/LAPACK ABIs with `64_` suffix

[ViralBShah]

Julia ships with openblas (w/lapack) compiled to have the suffix 64_ in the 64-bit case. This is a convention that many libraries have started adopting. It would be great for the sundials build to provide this name mangling option.

Currently we carry this patch for fortran: https://github.com/JuliaPackaging/Yggdrasil/blob/master/S/Sundials%405/bundled/patches/Sundials_Fortran.patch

[balos1]

I like the idea of handling this with a CMake option like SUNDIALS_F77_FUNC_UNDERSCORES or SUNDIALS_F77_FUNC_CASE. I think we would probably allow a custom suffix to be set rather than having the 64_ specifically.

@gardner48 Since this will also effect the sundials F77 libraries when they are built, it may be worth exploring having separate name mangling macros for the sundials F77 libraries and LAPACK, although, it should not be necessary.

[gardner48]

@balos1 I agree it would be good to to have separate the macros for the F77 interfaces and LAPACK. It does happen (though I've not run into it before) that the LAPACK name mangling is different for the Fortran name mangling. I know hypre and PETSc both provide an option to set a different name mangling scheme for LAPACK. A separate macro/option would also allow for providing a scheme even when a Fortran compiler is not present.