code-health: remove c_ssize_t type wrapper

ctypes.c_ssize_t was introduced in Python 2.7 [1] and Python 3.2 [2].

1. https://docs.python.org/2.7/library/ctypes.html#ctypes.c_ssize_t
2. https://docs.python.org/3.2/library/ctypes.html#ctypes.c_ssize_t

Part of #212

tarantool/connection.py

@@ -17,10 +17,7 @@
 
 import ctypes
 import ctypes.util
-try:
-    from ctypes import c_ssize_t
-except ImportError:
-    from ctypes import c_longlong as c_ssize_t
+from ctypes import c_ssize_t
 
 import msgpack