These were probably added to detect more qstrs but as long as the
micropython executable itself doesn't use the same build options the qstrs
would be unused anyway. Furthermore these definitions are for internal use
and get enabled when corresponding MICROPY_EMIT_XXX are defined, in which
case the compiler would warn about symbol redefinitions since they'd be
defined both here and in the source.
During make, makemoduledefs.py parses the current builds c files for
MP_REGISTER_MODULE(module_name, obj_module, enabled_define)
These are used to generate a header with the required entries for
"mp_rom_map_elem_t mp_builtin_module_table[]" in py/objmodule.c
Use overrideable properties instead of hardcoding the use of the
default cl executable used by msvc toolsets. This allows using
arbitrary compiler commands for qstr header generation.
The CLToolExe and CLToolPath properties are used because they are,
even though absent from any official documentation, the de-facto
standard as used by the msvc toolsets themselves.
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.
