[WIP] Interrupts pins samd51

[sago35]

#1094

I wrote the code for SAMD51J19A.
I checked with feather-m4 and it seems to be working fine.
I haven't confirmed this with the SAMD51J20A yet.

https://github.com/sago35/tinygo/tree/interrupts-pins-samd51

I'm struggling with how to write the following parts.
Is there a better way to do it?

1. sam.EIC.CTRLA.Set(0) or sam.EIC.CTRLA.ClearBits(0x02)
   • https://github.com/sago35/tinygo/blob/interrupts-pins-samd51/src/machine/machine_atsamd51.go#L352
2. Is it better to define it outside of SetInterrupt()?
   • https://github.com/sago35/tinygo/blob/interrupts-pins-samd51/src/machine/machine_atsamd51.go#L384
3. I'd like to write a little nicer, but interrupt.New() only accepts const values, so this is how it's implemented.
   • https://github.com/sago35/tinygo/blob/interrupts-pins-samd51/src/machine/machine_atsamd51.go#L393
4. I want to make an example, but the feather-m4 I have doesn't have a button.
   Creating an example for pybadge is one thing, but since there is no machine.Button, the other examples need to be modified.

[sago35]

I checked with feather-m4 d51j19 and pyportal d51j20 and it seems to be working fine.
I haven't confirmed this with the SAMD51P19 yet.
d51p19 has 128 pins.

[deadprogram]

Hello @sago35 now that PR #1094 has been merged into dev branch, your PR will need to be rebased to resolve the merge conflicts, please.

[deadprogram]

Actually, seems like you might need to git cherry-pick the commit from this PR into a new PR. Github closed your PR automatically when I deleted the branch that it was based on, since that branch was not the dev branch. Sorry about that!