Changes are:
- string0 is no longer built when building for host as the target, because
it'll be provided by the system libc and may in some cases clash with the
system one (eg on OSX).
- mp_int_t/mp_uint_t are defined in terms of intptr_t/uintptr_t to support
both 32-bit and 64-bit builds.
- Configuration values which are the default in py/mpconfig.h are removed
from mpconfigport.h to make the configuration a bit more minimal, eg as
a better starting point for new ports.
To enable lazy loading of submodules (among other things), which is very
useful for MicroPython libraries that want to have optional subcomponents.
Disabled explicitly on minimal ports.
Configurable via MICROPY_PY_BUILTINS_STR_COUNT. Default is enabled.
Disabled for bare-arm, minimal, unix-minimal and zephyr ports. Disabling
it saves 408 bytes on x86.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
