Auto merge of #125854 - beetrees:zst-arg-abi, r=estebank

Move ZST ABI handling to `rustc_target`

Currently, target specific handling of ZST function call ABI (specifically passing them indirectly instead of ignoring them) is handled in `rustc_ty_utils`, whereas all other target specific function call ABI handling is located in `rustc_target`. This PR moves the ZST handling to `rustc_target` so that all the target-specific function call ABI handling is in one place. In the process of doing so, this PR fixes #125850 by ensuring that ZST arguments are always correctly ignored in the x86-64 `"sysv64"` ABI; any code which would be affected by this fix would have ICEd before this PR. Tests are also added using `#[rustc_abi(debug)]` to ensure this behaviour does not regress.

Fixes #125850

src/tools/compiletest/src/command-list.rs

@@ -92,10 +92,12 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "ignore-nvptx64-nvidia-cuda",
     "ignore-openbsd",
     "ignore-pass",
+    "ignore-powerpc",
     "ignore-remote",
     "ignore-riscv64",
     "ignore-s390x",
     "ignore-sgx",
+    "ignore-sparc64",
     "ignore-spirv",
     "ignore-stable",
     "ignore-stage1",
@@ -123,6 +125,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "ignore-x86",
     "ignore-x86_64",
     "ignore-x86_64-apple-darwin",
+    "ignore-x86_64-pc-windows-gnu",
     "ignore-x86_64-unknown-linux-gnu",
     "incremental",
     "known-bug",
@@ -191,7 +194,9 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "only-msvc",
     "only-nightly",
     "only-nvptx64",
+    "only-powerpc",
     "only-riscv64",
+    "only-s390x",
     "only-sparc",
     "only-sparc64",
     "only-stable",