Drop itanium_demangler dependency

Index: angr/knowledge_plugins/functions/function.py
--- angr/knowledge_plugins/functions/function.py.orig
+++ angr/knowledge_plugins/functions/function.py
@@ -6,8 +6,6 @@ from collections import defaultdict
 from typing import Union, Optional, Iterable, Set
 from typing import Type
 
-from itanium_demangler import parse
-
 from cle.backends.symbol import Symbol
 from archinfo.arch_arm import get_real_address_if_arm
 import claripy
@@ -1570,6 +1568,7 @@ class Function(Serializable):
 
     @property
     def demangled_name(self):
+        """
         if self.name[0:2] == "_Z":
             try:
                 ast = parse(self.name)
@@ -1577,6 +1576,7 @@ class Function(Serializable):
                 return self.name
             if ast:
                 return ast.__str__()
+        """
         return self.name
 
     def get_unambiguous_name(self, display_name: Optional[str] = None) -> str:
