Unrolled build for rust-lang#133411

Rollup merge of rust-lang#133411 - RalfJung:emscripten-is-on-wasm, r=workingjubilee

the emscripten OS no longer exists on non-wasm targets

rust-lang#117338 removed our asmjs targets, which AFAIK means that emscripten only exists on wasm targets. However at least one place in the code still checked "is wasm or is emscripten". Let's fix that.

Cc ```@workingjubilee```

compiler/rustc_target/src/spec/tests/tests_impl.rs

@@ -19,6 +19,9 @@ impl Target {
         if self.is_like_msvc {
             assert!(self.is_like_windows);
         }
+        if self.os == "emscripten" {
+            assert!(self.is_like_wasm);
+        }
 
         // Check that default linker flavor is compatible with some other key properties.
         assert_eq!(self.is_like_osx, matches!(self.linker_flavor, LinkerFlavor::Darwin(..)));
@@ -137,7 +140,7 @@ impl Target {
             assert!(self.dynamic_linking);
         }
         // Apparently PIC was slow on wasm at some point, see comments in wasm_base.rs
-        if self.dynamic_linking && !(self.is_like_wasm && self.os != "emscripten") {
+        if self.dynamic_linking && !self.is_like_wasm {
             assert_eq!(self.relocation_model, RelocModel::Pic);
         }
         if self.position_independent_executables {