make sure DEFAULTDEVICE starts with "/dev/"
http://bugs.gentoo.org/91977

--- volname.c
+++ volname.c
@@ -39,6 +39,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <stdlib.h>
 
 int main(int argc, char *argv[])
 {
@@ -52,7 +53,7 @@
   if (argc == 2) {
     device = argv[1];
   } else if (argc == 1) {
-    device = DEFAULTDEVICE;
+    device = "/dev/" DEFAULTDEVICE;
   } else {
     fprintf(stderr, _("usage: volname [<device-file>]\n"));
     exit(1);