py: Fix some macros defines; cleanup some includes.
unix: Allow -X heapsize number take 'w' specifier for word size adjustment.

The specifier should go after the number, before size suffix like 'k' or 'm'.
E.g.: "-X heapsize=100wk" will use 100K heap on 32-bit system and 200K - on
64-bit.
py: Deactivate more code without MICROPY_PY_SYS

When compiler optimization has been turned on, gcc knows that this code
block is not going to be executed. But with -O0 it complains about
path_items being used uninitialized.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
bare-arm: Add dummy __assert_func and __fatal_error

Required to build bare-arm with debugging.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
stmhal: Declare variables extern in include files

Else we end up with several instances of the variable.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
py: Add order-only dependency for py-version.h

Else the directory might not exist.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>