Generate assembly listing on compile

[brycecherry75]

I noted that Wayne Holder's ATTiny10IDE generates an assembly listing on build which helps identify any latency such as from a timer interrupt until the first actual line of code is executed such as in Paul Stoffregen's FreqCount library - including such a feature would be helpful for myself and other programmers.

[per1234]

Here's how we set up disassembler listing output in ATTinyCore:
https://github.com/SpenceKonde/ATTinyCore/blob/83465cbccd31f95aed11a3a5712b1a862642b814/avr/platform.txt#L82-L87