Fix a bug in cptr_to_u64 in emulation

Author: ronnuriel

src/runtime/lpython/lpython.py

@@ -773,10 +773,10 @@ def __repr__(self):
     return ctypes_c_void_p()
 
 def cptr_to_u64(cptr):
-    return ctypes.addressof(cptr)
+    return u64(ctypes.cast(cptr, ctypes.c_void_p).value)
 
 def u64_to_cptr(ivalue):
-    return ctypes.c_void_p(ivalue)
+    return ctypes.c_void_p(i64(ivalue))
 
 def sizeof(arg):
     return ctypes.sizeof(convert_type_to_ctype(arg))