e.g., allocating a 192x32x6bpp matrix would be enough to trigger this
reliably on a Metro M4 Express using the "memory hogging" layout.
Allocating 64x32x6bpp could trigger it, but somewhat unreliably.
There are several things going on here:
* we make the failing call with interrupts off
* we were throwing an exception with interrupts off
* protomatter failed badly in _PM_free when it was partially-initialized
Incorporate the fix from protomatter, switch to a non-throwing malloc
variant, and ensure that interrupts get turned back on.
This decreases the quality of the MemoryError (it cannot report the size
of the failed allocation) but allows CircuitPython to survive, rather
than faulting.
This gets all the purely internal references. Some uses of
protomatter/Protomatter/PROTOMATTER remain, as they are references
to symbols in the Protomatter C library itself.
