Another toolchain update request thread.

I think it's time to update again. `7-2017-q4-major` [has some very process-breaking bugs](https://bugs.launchpad.net/gcc-arm-embedded/+bug/1698539)
See [here ](https://github.com/arduino/arduino-cli/issues/1286)for another thread discussing these issues.
I do not want to have to modify all of my code, or create intermediate compiler flag modification scripts that won't be supported across toolchains, etc. to have a hard dependency on dealing with these issues.

I downloaded the latest LTS `gcc-arm-none-eabi-10-2020-q4-major` from [here](https://launchpad.net/gcc-arm-embedded/+announcement/28093) and extracted it into the current toolchain's `7-2017q4`, and so far I have had no issues.

What kind of testing would it take to upgrade compilers? Do we have any tests defined?

No source files or existing tests are named. Start by reviewing the current 7-2017q4 toolchain setup, the gcc-arm-none-eabi-10-2020-q4-major result described here, and the linked issue threads; done means defining compatibility tests and confirming whether the compiler can be upgraded without requiring code or flag changes.

Written by the indexing model from the issue text.