run-make-support: Calculate artifact names for target platform, not host platform
This was implemented incorrectly during the porting process, where we relied on std consts. However, `run-make-support` is a host-only library, which meant that these artifact names were for the *host* and not the *target*.
Helps with #138066.
r? `@Kobzol`
try-job: armhf-gnu
try-job: test-various
try-job: x86_64-msvc-1
try-job: i686-msvc-1
try-job: x86_64-mingw-1
try-job: aarch64-apple
try-job: x86_64-apple-1
9ffde4b089