Do not show address for (pseudo) instructions with no code
While such instructions do not appear in GDB-produced disassembly,
they may appear in some manually-generated instruction lists.
One example of such (pseudo) instruction is label.
# References
1. [Debugging with GDB][1]
1. Using rr and Visual/VM Debugger to debug Smalltalk/X crash
* [blog post][2]
* [talk at Smalltalks 2019][3]
[1]: https://sourceware.org/gdb/onlinedocs/gdb/
[2]: https://janvrany.github.io/2018/09/vdb-01.html
[3]: https://youtu.be/Qbu4ED8wPYE