stubs for user error handling functions
stubs for user error handling functions

- set_error_handler, restore_error_handler
- set_exception_handler, restore_exception_handler

iolevel/peachpie-concept,peachpiecompiler/peachpie,iolevel/peachpie,iolevel/peachpie,iolevel/peachpie-concept,iolevel/peachpie,peachpiecompiler/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept