signing-party: gpgparticipants: not working on OSX

```data``` on OSX behave differently from the linux version.

Closes #21628.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
signing-party: style nits
wxmac: add arch flags

When using as a dependency for SAGA GIS, the missing architecture flags causes
it to fail. These extra flags help it compile correctly.

Closes #21179.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>