jitterentropy-library

AIX: process timestamp correctly

prepare release 3.6.2

Bump copyright year

Improve keyword portability

Simplify the delta calculation. Essentially equivalent to the approach in https://github.com/smuellerDD/jitterentropy-library/pull/139 which fixes tests/raw-entropy/validation-runtime-kernel/extractlsb.c but this PR also fixes tests/raw-entropy/validation-restart-kernel/extractlsb.c.