v2.12.3: Dec 12 2023

### Regressions

- parser: Fix namespaces redefined from default attributes

### Build fixes

- include: Rename XML_EMPTY helper macro
- include: Move declaration of xmlInitGlobals
- include: Add missing includes
- include: Move globals from xmlsave.h to parser.h
- include: Readd circular dependency between tree.h and parser.h