Make pw_getrandom() more usable by handling the EINTR case and returning
< 0 when there was an error or not enough random data was available.
Make a new pw_random() function that uses pw_getrandom() but falls back
to a pseudo random number generator otherwise. This pseudo random number
generator is seeded with either data from the urandom source or from the
current time when pipewire is initialized.
In most cases where crytographic security is not required pw_random()
should be easier to use.
