Fix configure options using AC_ARG_ENABLE Configure options to disable some features, which are checked using AC_ARG_ENABLE can be invoked with --enable-<option> as well. The current configure script always generates a #define for such options even though the --enable-<option> case should not generate a #define. Fix this by properly checking if the feature should be enabled, in which case no #define is being generated. Signed-off-by: Stefan Hauser <[email protected]>