Add failsafe against duplicate UUID's generated by threaded programs

Add in randomness based on Linux's thread id (gettid) to avoid race
conditions when two threads try to generate uuid's at the same time.
This shouldn't be an issue if /dev/urandom has proper locking and is
present, so this is just a failsafe.

Addresses SourceForge Bug: #1529672

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
5 files changed