default to stabs, from the GCC3 tree

gnu/dist/gcc4/gcc/config/i386/netbsd-elf.h

@@ -20,6 +20,10 @@ along with GCC; see the file COPYING.  If not, write to
 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 Boston, MA 02110-1301, USA.  */
 
+/* Use stabs instead of DWARF debug format.  */
+#undef  PREFERRED_DEBUGGING_TYPE
+#define PREFERRED_DEBUGGING_TYPE DBX_DEBUG
+
 #define TARGET_OS_CPP_BUILTINS()		\
   do						\
     {						\