Rollup merge of #143846 - usamoi:gc, r=bjorn3

pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests

Exported symbols are added as GC roots in linking, so `--gc-sections` won't hurt `-Zexport-executable-symbols`.

Fixes the run-make test to work on Linux. Enable the ui test on more targets.

cc rust-lang/rust#84161

Author: matthiaskrgr