Fix rootperm target because on DLD id does not understand -u

Makefile

@@ -117,7 +117,8 @@ modules: $(KERNELDIR)/include/linux/version.h
 	done
 
 rootperm:
-	@if [ `id -u` != 0 ] ; then \
+	@echo 'main(int argc,char**argv){unlink(argv[0]);return(getuid()==0);}'>g
+	@if gcc -x c -o G g && rm -f g && ./G ; then \
 		echo -e "\n\n      Need root permission for installation!\n\n"; \
 		exit 1; \
 	fi