xdu.c: correctly parse output from du

Former version would also take leading numbers
from du records.
(Closes github issue #26)

xdu.c

@@ -300,10 +300,8 @@ static void parse_file(char* filename)
 	 */
         sscanf(buf, "%lld", &size);
         buff = buf;
-        while ((*buff >= '0' && *buff <= '9')
-            || (*buff == ' ' || *buff == '\t')) {
-            buff++;
-        }
+        while (*buff != ' ' && *buff != '\t') { buff++; }
+        while (*buff == ' ' || *buff == '\t') { buff++; }
         strncpy(name, buff, strlen(buff) - 1);
         name[strlen(buff) - 1] = '\0';
         /*