Make python2 use our libffi library in case that is present in our requirements

This is only necessary for python2 because in python3 the configure option that we use in python2 has been removed

Author: opacam

pythonforandroid/recipes/python2/__init__.py

@@ -56,6 +56,11 @@ def prebuild_arch(self, arch):
 
     def set_libs_flags(self, env, arch):
         env = super(Python2Recipe, self).set_libs_flags(env, arch)
+        if 'libffi' in self.ctx.recipe_build_order:
+            # For python2 we need to tell configure that we want to use our
+            # compiled libffi, this step is not necessary for python3.
+            self.configure_args += ('--with-system-ffi',)
+
         if 'openssl' in self.ctx.recipe_build_order:
             recipe = Recipe.get_recipe('openssl', self.ctx)
             openssl_build = recipe.get_build_dir(arch.arch)