In particular, unix outputs to stderr, to allow to run testsuite against
micropython built with debug output (by redirecting stderr to /dev/null).

If there's malloc and memset, then there's no need for calloc, especially if
we need to implement it ourselves.

To alloc complete memory alloc flow tracing.

mpconfig.h will automatically pull mpconfigport.h.

This is just max value of current_bytes_allocated seen.

Unlike total_bytes_allocated, this tracks m_free()'s too.