Include ISA-specific information in verifier errors.

When the test driver reports a verifier error, make sure to include the
TargetIsa when printing the failing function.

cranelift/src/filetest/runone.rs

@@ -118,7 +118,7 @@ fn run_one_test<'a>(tuple: (&'a SubTest, &'a Flags, Option<&'a TargetIsa>),
     // Should we run the verifier before this test?
     if !context.verified && test.needs_verifier() {
         verify_function(&func, isa)
-            .map_err(|e| pretty_verifier_error(&func, e))?;
+            .map_err(|e| pretty_verifier_error(&func, isa, e))?;
         context.verified = true;
     }