Remove the symtable.h header file and the undocumented functions:

• PyST_GetScope()
• PySymtable_Build()
• PySymtable_BuildObject()
• PySymtable_Free()
• Py_SymtableString()
• Py_SymtableStringObject()

The Py_SymtableString() function was part the stable ABI by mistake but it could not be used, because the symtable.h header file was excluded from the limited C API.

The Python :mod:`symtable` module remains available and is unchanged.

Patch by Victor Stinner.