Emit progress along with the current target triple, in order to provide more context during the long porting process.

Example log messages:

building aarch64-apple-darwin (1/43)
building aarch64-unknown-linux-gnu (2/43)
building aarch64-unknown-linux-musl (3/43)
...
building x86_64-unknown-netbsd (43/43)
copied artifacts to .crit/bin

we could pad out the target triple names like with --list, for ease of reading