little test for comparing loop code

tests/run/addloop.pyx

+__doc__ = """
+    >>> x = 1
+    >>> for i in range(10):
+    ...     x = x + i
+    >>> x
+    46
+
+    >>> add_pyrange(10)
+    46
+    >>> add_py(10)
+    46
+    >>> add_c(10)
+    46
+"""
+
+def add_pyrange(max):
+    x = 1
+    for i in range(max):
+        x = x + i
+    return x
+
+def add_py(max):
+    x = 1
+    for i from 0 <= i < max:
+        x = x + i
+    return x
+
+def add_c(max):
+    cdef int x,i
+    x = 1
+    for i from 0 <= i < max:
+        x = x + i
+    return x