Test failures on powerpc64(le)-unknown-linux-musl

[Gelbpunkt]

This is more of a tracking issue for getting ./x.py test passing on powerpc64le-unknown-linux-musl. I'll try to PR some fixes for these in the next days, posting this issue to make sure this is tracked somewhere. I'll also be testing big endian musl later today.

First and foremost, bootstrap.py always downloads a stage0 toolchain with -unknown-linux-gnu suffix, which is suboptimal and won't work on musl targets. I have a rather hacky local patch that checks ldd --version for musl and use the musl triple in that case. I wonder if there's a better way to detect it?

Anyways, currently, 3 tests fail:

    [ui] tests/ui/codegen/duplicated-path-in-error.rs
    [ui] tests/ui/print-request/supported-crate-types.rs#musl
    [ui] tests/ui/stats/input-stats.rs

duplicated-path-in-error.rs:

---- [ui] tests/ui/codegen/duplicated-path-in-error.rs stdout ----
diff of stderr:

-	error: couldn't load codegen backend /non-existing-one.so: cannot open shared object file: No such file or directory
+	error: couldn't load codegen backend /non-existing-one.so: Error loading shared library /non-existing-one.so: No such file or directory
2	
3	

supported-crate-types.rs#musl:

---- [ui] tests/ui/print-request/supported-crate-types.rs#musl stdout ----
diff of stdout:

1	bin
+	cdylib
+	dylib
2	lib
3	proc-macro
4	rlib

It doesn't really like that I did export RUSTFLAGS="-C target-feature=-crt-static" which was required for building stage1 natively.

input-stats.rs:

error[E0658]: inline assembly is not stable yet on this architecture
  --> /home/adrian/rust/tests/ui/stats/input-stats.rs:52:14
   |
LL |     unsafe { asm!("mov rdi, 1"); }
   |              ^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #93335 <https://github.com/rust-lang/rust/issues/93335> for more information
   = help: add `#![feature(asm_experimental_arch)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

Inline assembly isn't stable on powerpc yet (I wonder what would actually be missing to stabilize it other than someone pushing for it?).

[Gelbpunkt]

First one is #128474