srand: make integer seeding only depend on the *value* of the seed.

This guarantees that no matter what the type of an integer seed
used to seed the RNG, the same seed vector will result, depending
only on the value of seed given. This ensures identical behavior
on 32-bit and 64-bit systems if integer literals are used for
seeding. If you want more control over the seed vector, supply an
actual Vector{Uint32} of seed data.

This reverts commit 370f0334a3ad0e6c8c8e44a6e2c7ab041a960f67.