option('gnome_proxy', type: 'feature', value: 'auto', description: 'support for GNOME desktop proxy configuration')
option('installed_tests', type: 'boolean', value: false, description: 'enable installed tests')
option('static_modules', type: 'boolean', value: false, description: 'build static modules')
+option('default_ca_file', type: 'string', value: '', description: 'set default CA file')