Takes care to properly link libraries with python depending on our
        requirements and the attribute :attr:`opt_depends`.

def set_libs_flags(self, env, arch):
        '''Takes care to properly link libraries with python depending on our
        requirements and the attribute :attr:`opt_depends`.
        '''
        def add_flags(include_flags, link_dirs, link_libs):
            env['CPPFLAGS'] = env.get('CPPFLAGS', '') + include_flags
            env['LDFLAGS'] = env.get('LDFLAGS', '') + link_dirs
            env['LIBS'] = env.get('LIBS', '') + link_libs

        if 'sqlite3' in self.ctx.recipe_build_order:
            info('Activating flags for sqlite3')
            recipe = Recipe.get_recipe('sqlite3', self.ctx)
            add_flags(' -I' + recipe.get_build_dir(arch.arch),
                      ' -L' + recipe.get_lib_dir(arch), ' -lsqlite3')

        if 'libffi' in self.ctx.recipe_build_order:
            info('Activating flags for libffi')
            recipe = Recipe.get_recipe('libffi', self.ctx)
            # In order to force the correct linkage for our libffi library, we
            # set the following variable to point where is our libffi.pc file,
            # because the python build system uses pkg-config to configure it.
            env['PKG_CONFIG_PATH'] = recipe.get_build_dir(arch.arch)
            add_flags(' -I' + ' -I'.join(recipe.get_include_dirs(arch)),
                      ' -L' + join(recipe.get_build_dir(arch.arch), '.libs'),
                      ' -lffi')

        if 'openssl' in self.ctx.recipe_build_order:
            info('Activating flags for openssl')
            recipe = Recipe.get_recipe('openssl', self.ctx)
            add_flags(recipe.include_flags(arch),
                      recipe.link_dirs_flags(arch), recipe.link_libs_flags())
        return env