Name of the libraries when GALAHAD is compiled with 64-bit integer

[amontoison]

We should decide what is the name of the static / shared libraries when we use 64-bit integer. With 32-bit integer, we generate libgalahad_single and libgalahad_double. I suggest libgalahad64_single and libgalahad64_double.

cc @nimgould

[nimgould]

elsewhere we have reversed things so that packages are _single_64 not 64_single

[amontoison]

Ok, so we should go with libgalahad_double_64.so or libgalahad_double64.so. For libHSL, I generate a libhsl64.so.