[PD] pthread external template

[patrick]

Hi Charles,

Since i needed to call libusb and it was causing a glitch in the DSP, i 
had to use pthread.

> some of the routines can be wrapped up with (or called from) the pthread templates?

No, it's only a template (with a Makefile) as a starting point to code 
your own custom external. Maybe you should have a look at grh/threadlib/:

PD objects for threaded patching:
- detach    run part of the patch in a helper thread
- join        synchronize messages to pd's main thread

Also, i am not sure how good is my pthread template... I am not using 
sys_lock / unlock anywhere. It works, but maybe there's a huge mistake 
there.

patrick