Master clock port sharing could cause a resource dependency exception

[larry-xmos]

Audio hub and PDM microphone tasks share master clock port. There are instructions during the setting up of clock blocks and ports in these tasks that take the master clock port's resource ID as an operand. Two of these could theoretically execute close to each other and cause a resource trap.

To prevent this I would suggest serialising the setup sequences of the two tasks.

[xross]

This is already done on master which also avoids the unsafe

[xross]

https://github.com/xmos/lib_xua/commit/a8562ad56a7287f77f83a8bc1e024947a2af6a04