Add memory profiling in PIO2

Add memory profiling information along with the timing logs.

bget buffer allocator has some memory statistics that we can use.
We might have to add some support for cases where malloc()
(PIO_USE_MALLOC) is used instead of bget memory blocks.

To account for memory used up by malloc/frees we can change
them to macros with built-in memory statistics collection.

It would be useful to print out the memory usage of PIO at the
beginning of a PIO call and at the end of a PIO call. If possible,
it would also be beneficial to add the memory usage of the
application here.