cmd/cgo/internal/swig,cmd/go,x/build: swig cgo tests incompatible with C++ toolchain on builders

[mknyszek]

After updating the builder images to have a gcc-based C++ toolchain, the clang and 386 builders began failing. This appears to be because the toolchain that's installed is either incompatible with the object files produced by cgo and the Go toolchain (my theory for clang) or the toolchain just can't properly cross-compile (my theory for 386).

Thing is, these tests were already getting skipped 100% of the time, or not running at all, looking at the history. So for now, they're skipped once again. This bug tracks possibly enabling these tests, but I don't think they're a particularly high priority.

Example failures:

• https://ci.chromium.org/ui/p/golang/builders/ci/gotip-linux-386/b8746588762099038993/overview
• https://ci.chromium.org/ui/p/golang/builders/ci/gotip-linux-386-clang15/b8746588763037378577/overview
• https://ci.chromium.org/ui/p/golang/builders/ci/gotip-linux-amd64-clang15/b8746588762291961633/overview

[gopherbot]

Change https://go.dev/cl/588938 mentions this issue: cmd/cgo/internal/swig,cmd/go: skip swig tests on 386 and clang

[gopherbot]

Change https://go.dev/cl/589195 mentions this issue: cmd/cgo/internal/swig,cmd/go: reenable swig tests on 386

[gopherbot]

Change https://go.dev/cl/589175 mentions this issue: env: add g++-multilib for running swig tests on 386

[gopherbot]

Change https://go.dev/cl/589295 mentions this issue: cmd/cgo/internal/testsanitizers: skip some libfuzzer tests in short mode

[gopherbot]

Change https://go.dev/cl/589296 mentions this issue: cmd/cgo/internal/swig: force use of lld for LTO tests on the builders

[mknyszek]

Erroneously closed, but will be closed soon.