Add elf-dump utility

Adds an `elf-dump` utility that basically wraps `objdump` to print out file offsets for disassembled instructions.  Makes patching with things other than `elf-patch` easier.

```
$ objdump -d lateot | grep fork
080489ac <fork@plt>:
 80496a9:       e8 fe f2 ff ff          call   80489ac <fork@plt>
$ elfdump lateot | grep fork
000009ac <fork@plt> (File Offset: 0x9ac):
    16a9:       e8 fe f2 ff ff          call   9ac <fork@plt> (File Offset: 0x9ac)
$ xxd  -l5 -s $((0x16a9)) lateot
00016a9: e8fe f2ff ff                             .....
```