Fix library name and path on some 64bit systems

I have updated the behaviour as you suggested. This resolves the problem and keep the property you desire.

I does not use cross-compiling now, but want in future and this behaviour with ARCH_SUFFIX makes linking a bit complicated (when library is crosscompiled but application is build natively, there must be guess algorithm for library name trying both -lswiftnav nad -lswiftnav-SOMETHING). Would you like to please consider removing this feature?

PS: Please do not use patch from fix_64-01, it contains bug for crosscompiling (resets LIB_SUFFIX value). I would happily make another patch, if you want .