Update more rustc/libtest things for wasm64

* Add wasm64 variants for inline assembly along the same lines as wasm32
* Update a few directives in libtest to check for `target_family`
  instead of `target_arch`
* Update some rustc codegen and typechecks specialized for wasm32 to
  also work for wasm64.

compiler/rustc_codegen_llvm/src/asm.rs

@@ -320,7 +320,7 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                 InlineAsmArch::Mips | InlineAsmArch::Mips64 => {}
                 InlineAsmArch::S390x => {}
                 InlineAsmArch::SpirV => {}
-                InlineAsmArch::Wasm32 => {}
+                InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => {}
                 InlineAsmArch::Bpf => {}
             }
         }