On 64 bit machines where long int types AND long long int types are both 8 bytes, NSPR truncates
64-bit values to 32-bits.  This is actually by designed based on the comment here:
https://bugzilla.mozilla.org/show_bug.cgi?id=433029

however, this is not what we want.  We don't use NSPR types everywhere, so we need to handle this
case differently than NSPR's original intent for their own types.