Enhance sqlite3_randomness(N,P) such that it resets the internal PRNG
if N is less than 1.  Subsequent calls to sqlite3_randomness() will reinitialize
the internal PRNG by calling the xRandomness() method of the default VFS.
Try to detect process ID changes due to fork() calls in os_unix.c and
reset the PRNG when a process ID change is detected.