Rollup merge of #144235 - Gelbpunkt:run-make-musl, r=jieyouxu

Fix run-make tests on musl hosts

On musl hosts, we already set `-Ctarget-feature=-crt-static` and `IS_MUSL_HOST=1` in compiletest. However, in order for the run-make tests to compile fine on musl hosts, we need to propagate this flag in our rustc invocations to ensure we can generate cdylibs.

Author: jhpratt