- Unifdef USE_WEAK_SEEDING since it is too obsolete to support and makes
reading hard.
- Instead of doing range transformation in each and every function here,
do it single time directly in do_rand(). One "mod" operation overhead is not
a big deal, but the code looks nicer and possible future functions additions
or PRNG change do not miss range transformations neither have unneeded ones.
- Use POSIX argument types for visible functions (cosmetic).
MFC after: 1 week