fix(r/adbcsnowflake): Fix configuration of adbcsnowflake when configure is run from a git shell

[paleolimbot]

Closes #2767

It seems like the RTools shell identifies itself as MSYS_NT... whereas the git shell identifies itself as MINGW64_NT.... It looks like r-universe configures using the git shell? We can support both!

[lidavidm]

Ah, sorry, I cut the release before I saw these PRs...

[jeroen]

It seems like the RTools shell identifies itself as MSYS_NT...

For reference, this depends on how you start msys2. Any msys2 installation can be started in different modes, which have separate shells and icons, and different compilers and uname.

The MSYS mode is intended to build executables for use by msys2 itself; the resulting binaries depend on the msys2 runtime and will not work other windows systems. To compile software with mingw64 that can run on any windows system without msys2 (as R does) you need start msys2 in MINGW64 mode.

[paleolimbot]

Ah, sorry, I cut the release before I saw these PRs...

No worries! The timing was unrelated 🙂

For reference, this depends on how you start msys2

Thanks for the background!