That patch no longer applies without merge conflicts.
I just noticed that there was a discussion a year ago
when other developers suggested to use libuuid.
We can see the result of that discussion in the current code:
QEMU does not use libuuid, not even functions with the
same interface. Nor does it include a function to generate
a new UUID value.
There were arguments why QEMU would not need
UUID generation in its code. The VDI block driver
needs UUID generation unless we are satisfied with
dummy or zero values.