Disable portable build by default

The default value of a boolean meson option is true. We want
non-portable build by default.

meson_options.txt

@@ -3,6 +3,6 @@ option('build_server', type: 'boolean', value: true, description: 'Build the ser
 option('crossbuild_windows', type: 'boolean', value: false, description: 'Build for Windows from Linux')
 option('windows_noconsole', type: 'boolean', value: false, description: 'Disable console on Windows (pass -mwindows flag)')
 option('prebuilt_server', type: 'string', description: 'Path of the prebuilt server')
-option('portable', type: 'boolean', description: 'Use scrcpy-server.jar from the same directory as the scrcpy executable')
+option('portable', type: 'boolean', value: false, description: 'Use scrcpy-server.jar from the same directory as the scrcpy executable')
 option('skip_frames', type: 'boolean', value: true, description: 'Always display the most recent frame')
 option('hidpi_support', type: 'boolean', value: true, description: 'Enable High DPI support')