[common.disable_warnings] ignore -Wdeprecated-register

dune/stuff/common/disable_warnings.hh

 #ifdef __GNUC__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wdeprecated-register"
 #pragma GCC diagnostic ignored "-Wignored-qualifiers"
 #pragma GCC diagnostic ignored "-Wextra"
 #pragma GCC diagnostic ignored "-Wmissing-field-initializers"