Use -gline-tables-only instead of -g1 on clang.

config.lib

@@ -1719,9 +1719,13 @@ EOL
 
 		if [ -n "$LIBBFD_LIBS" -o -n "$HAVE_GDB_DBG" ]; then
 			if [ $enable_debug -lt 1 ] && [ "$with_bfd_extra_debug" = "1" ]; then
+				if [ -n "`basename "$cc_host" | grep "clang" 2>/dev/null`" ]; then
+					CFLAGS="$CFLAGS -gline-tables-only"
+				else
 					CFLAGS="$CFLAGS -g1"
 				fi
 			fi
+		fi
 
 		log 2 "executing $cc_host $CFLAGS $LDFLAGS $STATIC_FLAGS -o tmp.config.sigaction -x c++ - -ldl"
 		"$cc_host" $CFLAGS $LDFLAGS $STATIC_FLAGS -o tmp.config.sigaction -x c++ - -ldl 2> /dev/null << EOL