Fix probelms in 'memory.c' library

[ebranca]

Fix following problems in memory.c library.
Line 69:
|---> Initial value of MemoryType_members[0].offset is type int, expects Py_ssize_t: ((int)&((MemoryObject *)0)->size
Line 70:
|---> 70|Initializer block for MemoryType_members[1] has 1 field, but PyMemberDef has 5 fields
Line 96:
|---> Initializer block for MemoryType_members[1] has 1 field, but PyMethodDef has 4 fields
Line 257:
|---> Assignment of ssize_t to size_t
Line 266:
|---> Parameter end not used