gh-106287: Improve error handling in marshalling code

[chgnrdv]

Fixes#106287

Currently w_object and w_complex_object routines continue to marshal complex object until they return to their callers, regardless of error or exception occurred. This leads to ignored exceptions and, as a result, assertion failures in debug builds, e. g. if PyObject_GetBuffer is called during marshalling of complex object with exception being set. Another consequence is the late return from w_object in case of error: if arg is a container and the first item is unmarshallable, all other items will be processed anyway.
This fix improves error handling of some marshalling routines, making them to return status value (0 or 1) depending on whether an error occurred, and use this status to decide whether to marshal remaining objects or not.

• make w_object and w_complex_object functions to return 1 if marshalling succeeded and 0 if error occurred
• in w_object check if error occurred and return 0 in this case
• add W_OBJECT macro that calls w_object and returns 0 from function in which it is expanded
• make w_complex_object function to use W_OBJECT macro calls instead of w_object function calls
• change W_SIZE macro to return 0 on failure
• make w_pstring return 0 to avoid compiler warning

• Issue: Assertion failure when marshalling buffer object with exception being set #106287

[chgnrdv]

cc @brandtbucher