As explained at https://stackoverflow.com/a/49830956/1069307, 'asm' is a GNU
extension that will produce an error when using a non GNU standard like -std=c11.
With recent commit 9b1e06cd0cc7937ae291a34f1bb5ec1b4568faee having fixed our use
of -std=c11, the MIPS build failed with the error above.
With this sorted, we also re-enable the MIPS gcc build in GitHub Actions.
91cb708816