Get RT FIFO Status

[sgregor249]

Create an RT FIFO Primative similar to the Get Queue Status VI that returns the number of elements in the RT FIFO. Currently RT FIFO Read and RT FIFO Write return the number of elements in the RT FIFO, but calling these VIs will affect the contents of RT FIFO.

A workaround for this would be to maintain a count on a shift register and increment/decrement it each time the RT FIFO Write/RT FIFO Read VIs are called. This solution does not work when trying to monitor the size of an RT FIFO in a running VI in another VI that is used to detect memory leaks.