Include copy of GifQuantizeBuffer function from giflib

From https://github.com/coin3d/simage/pull/33
giflib 5.1.9 and above removes the GifQuantizeBuffer() function used in
simage_gif.c (see https://sourceforge.net/p/giflib/bugs/132/ and
https://sourceforge.net/p/giflib/bugs/142/).

The fix is either to remove the related check in simage_gif.c or to include a
copy of the function as encouraged by giflib, due the util library not being
included in installed versions of giflib (license is MIT):

    The undocumented and deprecated GifQuantizeBuffer() entry point has been
    moved to the util library to reduce libgif size and attack surface.
    Applications needing this function are couraged to link the util library or
    make their own copy.

bob/io/image/cpp/gif.cpp

@@ -25,6 +25,13 @@
 
 extern "C" {
 #include <gif_lib.h>
+
+#if GIFLIB_MAJOR > 5 || GIFLIB_MAJOR == 5 && GIFLIB_MINOR >= 2 || GIFLIB_MAJOR == 5 && GIFLIB_MINOR == 1 && GIFLIB_RELEASE >= 9
+//see https://sourceforge.net/p/giflib/bugs/132/
+//and https://sourceforge.net/p/giflib/bugs/142/
+#include <quantize.h>
+#endif
+
 }
 
 // QuantizeBuffer function definition that was inlined (only) in giflib 4.2

bob/io/image/giflib/COPYING

+The GIFLIB distribution is Copyright (c) 1997  Eric S. Raymond
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

bob/io/image/giflib/quantize.h

+/***************************************************************************
+
+getarg.h - Support routines for the giflib utilities
+
+SPDX-License-Identifier: MIT
+
+**************************************************************************/
+
+#ifndef QUANTIZE_H
+#define QUANTIZE_H
+
+#include <gif_lib.h>
+
+/******************************************************************************
+ Color table quantization
+******************************************************************************/
+int GifQuantizeBuffer(unsigned int Width, unsigned int Height,
+                   int *ColorMapSize, GifByteType * RedInput,
+                   GifByteType * GreenInput, GifByteType * BlueInput,
+                   GifByteType * OutputBuffer,
+                   GifColorType * OutputColorMap);
+
+#endif /*QUANTIZE_H */
+
+/* end */

setup.py

@@ -10,6 +10,7 @@ from setuptools import setup, find_packages, dist
 dist.Distribution(dict(setup_requires=['bob.extension', 'bob.blitz'] + bob_packages))
 from bob.extension.utils import egrep, find_header, find_library
 from bob.blitz.extension import Extension, Library, build_ext
+from distutils.version import LooseVersion
 
 from bob.extension.utils import load_requirements
 build_requires = load_requirements()
@@ -334,6 +335,8 @@ system_include_dirs = [
     tiff_pkg.include_directory,
     gif_pkg.include_directory,
     ]
+if LooseVersion(gif_pkg.version) >= LooseVersion("5.1.9"):
+  system_include_dirs.append("bob/io/image/giflib")
 
 library_dirs = [
     jpeg_pkg.library_directory,