Rollup merge of #117338 - workingjubilee:asmjs-meets-thanatos, r=b-naber

Remove asmjs

Fulfills [MCP 668](rust-lang/compiler-team#668).

`asmjs-unknown-emscripten` does not work as-specified, and lacks essential upstream support for generating asm.js, so it should not exist at all.

Author: matthiaskrgr

src/shims/foreign_items.rs

@@ -345,7 +345,7 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         // List taken from `library/std/src/sys/common/alloc.rs`.
         // This list should be kept in sync with the one from libstd.
         let min_align = match this.tcx.sess.target.arch.as_ref() {
-            "x86" | "arm" | "mips" | "mips32r6" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
+            "x86" | "arm" | "mips" | "mips32r6" | "powerpc" | "powerpc64" | "wasm32" => 8,
             "x86_64" | "aarch64" | "mips64" | "mips64r6" | "s390x" | "sparc64" | "loongarch64" =>
                 16,
             arch => bug!("unsupported target architecture for malloc: `{}`", arch),