Basic test for multiple inheritance

nogil_test/cypclass_test_multiple_inheritance.pyx

+cdef cypclass A:
+  int a
+  void __init__(self, int arg=0):
+    self.a = arg
+
+  A __iadd__(self, A other):
+    self.a += other.a
+
+  int getter(self):
+    return self.a
+
+cdef cypclass B:
+  int b
+  void __init__(self, int arg=0):
+    self.b = arg
+
+  B __isub__(self, B other):
+    self.b -= other.b
+
+  int getter(self):
+    return self.b
+
+cdef cypclass C(A,B):
+  void __init__(self, int arg=0):
+    self.a = self.b = arg
+
+cpdef bag():
+  a = A(3)
+  b = B(4)
+  c = C(5)
+  c += a
+  c -= b
+  return str(a.a) + '\n' + str(b.b) + '\n' + str(c.a) + '\n' + str(c.b)\
+         + '\n' + str(A.getter(c)) + '\n' + str(B.getter(c))

nogil_test/cypclass_test_multiple_inheritance_distutil.py

+from distutils.core import setup
+from distutils.extension import Extension
+from Cython.Build import cythonize
+
+setup(
+    ext_modules = cythonize([
+        Extension(
+            'cypclass_test_multiple_inheritance',
+            language='c++',
+            sources=['cypclass_test_multiple_inheritance.pyx'],
+            extra_compile_args=["-pthread", "-std=c++11"],
+        ),
+    ])
+)
+