Add avr-fast-multiply

[adbancroft]

No description provided.

[github-actions]

Hi @adbancroft.
There was an unexpected failure during automated processing of your pull request.
This error is unrelated to the content of your pull request.

A maintainer has been notified and will investigate as soon as possible.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/adbancroft/avr-fast-multiply:

Linting library in avr-fast-multiply
WARNING: No example sketches found. Please provide examples.                                      
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#library-examples
         (Rule LD004)                                                                             

Linter results for project: 0 ERRORS, 1 WARNINGS

-------------------

[github-actions]

Your submission has now been accepted! Thanks for your contribution to the Arduino Library Manager index.

The library(s) will be available for installation via Library Manager within a day's time.

You can check the logs from the Library Manager indexer for your library(s) here:
http://downloads.arduino.cc/libraries/logs/github.com/adbancroft/avr-fast-multiply/