Adding cython v0.20.2 in third-party.

third_party/cython/src/Cython/Includes/cpython/mem.pxd

+cdef extern from "Python.h":
+
+    #####################################################################
+    # 9.2 Memory Interface
+    #####################################################################
+    # You are definitely *supposed* to use these: "In most situations,
+    # however, it is recommended to allocate memory from the Python
+    # heap specifically because the latter is under control of the
+    # Python memory manager. For example, this is required when the
+    # interpreter is extended with new object types written in
+    # C. Another reason for using the Python heap is the desire to
+    # inform the Python memory manager about the memory needs of the
+    # extension module. Even when the requested memory is used
+    # exclusively for internal, highly-specific purposes, delegating
+    # all memory requests to the Python memory manager causes the
+    # interpreter to have a more accurate image of its memory
+    # footprint as a whole. Consequently, under certain circumstances,
+    # the Python memory manager may or may not trigger appropriate
+    # actions, like garbage collection, memory compaction or other
+    # preventive procedures. Note that by using the C library
+    # allocator as shown in the previous example, the allocated memory
+    # for the I/O buffer escapes completely the Python memory
+    # manager."
+
+    # The following function sets, modeled after the ANSI C standard,
+    # but specifying behavior when requesting zero bytes, are
+    # available for allocating and releasing memory from the Python
+    # heap:
+
+    void* PyMem_Malloc(size_t n)
+    # Allocates n bytes and returns a pointer of type void* to the
+    # allocated memory, or NULL if the request fails. Requesting zero
+    # bytes returns a distinct non-NULL pointer if possible, as if
+    # PyMem_Malloc(1) had been called instead. The memory will not
+    # have been initialized in any way.
+
+    void* PyMem_Realloc(void *p, size_t n)
+    # Resizes the memory block pointed to by p to n bytes. The
+    # contents will be unchanged to the minimum of the old and the new
+    # sizes. If p is NULL, the call is equivalent to PyMem_Malloc(n);
+    # else if n is equal to zero, the memory block is resized but is
+    # not freed, and the returned pointer is non-NULL. Unless p is
+    # NULL, it must have been returned by a previous call to
+    # PyMem_Malloc() or PyMem_Realloc().
+
+    void PyMem_Free(void *p)
+    # Frees the memory block pointed to by p, which must have been
+    # returned by a previous call to PyMem_Malloc() or
+    # PyMem_Realloc(). Otherwise, or if PyMem_Free(p) has been called
+    # before, undefined behavior occurs. If p is NULL, no operation is
+    # performed.
+
+    # The following type-oriented macros are provided for
+    # convenience. Note that TYPE refers to any C type.
+
+    # TYPE* PyMem_New(TYPE, size_t n)
+    # Same as PyMem_Malloc(), but allocates (n * sizeof(TYPE)) bytes
+    # of memory. Returns a pointer cast to TYPE*. The memory will not
+    # have been initialized in any way.
+
+    # TYPE* PyMem_Resize(void *p, TYPE, size_t n)
+    # Same as PyMem_Realloc(), but the memory block is resized to (n *
+    # sizeof(TYPE)) bytes. Returns a pointer cast to TYPE*.
+
+    void PyMem_Del(void *p)
+    # Same as PyMem_Free().
+
+    # In addition, the following macro sets are provided for calling
+    # the Python memory allocator directly, without involving the C
+    # API functions listed above. However, note that their use does
+    # not preserve binary compatibility across Python versions and is
+    # therefore deprecated in extension modules.
+
+    # PyMem_MALLOC(), PyMem_REALLOC(), PyMem_FREE().
+    # PyMem_NEW(), PyMem_RESIZE(), PyMem_DEL().