ENH: turn on 64-bit ids on windows

Enable 64-bit ids on windows by default. This case is detected with
size_t is 64-bits but long is 32-bits. The ITK_USE_64BITS_IDS in
enable by default in this case with the superbuild.

Change-Id: Ic1ae748a8116a53f8cda0066a32ba8bed4eefd99
Merge topic 'SIMPLEITK-472_Enable64BitsIDSOnWindows' into next

750e24a6 ENH: turn on 64-bit ids on windows