Log2Lines: improve 32-64 bits support

Current code seems to work for "all 32 bits" case.
For what it's worth, Linux 64 with ROS 32 iso/log seems to work too.

Support for 64 bits seems incomplete,
especially with regard to size_t offset.

Wanted combinations:

• "Host": Linux or Windows.
• "Host": 32 or 64 bits.
• "Guest" (ReactOS): 32 or 64 bits.

ARM host/guest support is out of scope, for the time being.