meson: allow debug-threads to be disabled in debug

Reviewed-by: Marcel Hollerbach <mail@marcel-hollerbach.de>
Reviewed-by: Stefan Schmidt <stefan@datenfreihafen.org>
Differential Revision: https://phab.enlightenment.org/D11756

src/lib/eina/meson.build

@@ -302,7 +302,7 @@ if cc.has_header_symbol(pthread_np_header_file, 'pthread_attr_setaffinity_np', a
    eina_config.set('EINA_HAVE_PTHREAD_AFFINITY', '1')
 endif
 
-if debug_threads or get_option('debug-threads')
+if debug_threads and get_option('debug-threads')
    if cc.has_header_symbol('execinfo.h', 'backtrace')
       eina_config.set('EINA_HAVE_DEBUG_THREADS', '1')
    endif