Rollup merge of rust-lang#136339 - veera-sivarajan:ignore-arm-unknown-headers, r=jieyouxu

CompileTest: Add Directives to Ignore `arm-unknown-*` Targets

In  rust-lang#134626, I want to ignore `arm-unknown-*` targets because the LLVM IR for those looks very different compared to other targets: https://rust.godbolt.org/z/ssYMhdv4x.

I can use `ignore-arm` but, I think, it would exclude large number of Apple devices.

So this PR adds a few directives to ignore `arm-unknown-*` targets specifically.

Author: matthiaskrgr

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

@@ -39,6 +39,10 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "ignore-android",
     "ignore-apple",
     "ignore-arm",
+    "ignore-arm-unknown-linux-gnueabi",
+    "ignore-arm-unknown-linux-gnueabihf",
+    "ignore-arm-unknown-linux-musleabi",
+    "ignore-arm-unknown-linux-musleabihf",
     "ignore-avr",
     "ignore-beta",
     "ignore-cdb",