add option to print short list of all libraries

Add -a option to list all libraries, but without printing dependencies of lib, when printing this same lib next time.

Sample output with -a:

d$ ./tldd -a tldd
tldd
├─libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f4b12c6f000)
│ ├─libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f4b12aec000)
│ │ ├─libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f4b12911000)
│ │ │ └─ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 (0x00007f4b12e21000)
│ │ └─ld-linux-x86-64.so.2 ... see above
│ ├─libc.so.6 ... see above
│ ├─ld-linux-x86-64.so.2 ... see above
│ └─libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f4b12ad2000)
│   └─libc.so.6 ... see above
├─libm.so.6 ... see above
├─libgcc_s.so.1 ... see above
└─libc.so.6 ... see above