Enable exnref instrumentation when EH is enabled (#2379)

`exnref` is enabled by not reference type feature but exception handling
feature. Sorry that I missed this in #2377.

Author: aheejin

src/passes/InstrumentLocals.cpp

@@ -159,8 +159,10 @@ struct InstrumentLocals : public WalkerPass<PostWalker<InstrumentLocals>> {
 
     if (curr->features.hasReferenceTypes()) {
       addImport(curr, get_anyref, "aiia");
-      addImport(curr, get_exnref, "eiie");
       addImport(curr, set_anyref, "aiia");
+    }
+    if (curr->features.hasExceptionHandling()) {
+      addImport(curr, get_exnref, "eiie");
       addImport(curr, set_exnref, "eiie");
     }
   }

test/passes/instrument-locals_all-features.txt

@@ -15,8 +15,8 @@
  (import "env" "set_f32" (func $set_f32 (param i32 i32 f32) (result f32)))
  (import "env" "set_f64" (func $set_f64 (param i32 i32 f64) (result f64)))
  (import "env" "get_anyref" (func $get_anyref (param i32 i32 anyref) (result anyref)))
- (import "env" "get_exnref" (func $get_exnref (param i32 i32 exnref) (result exnref)))
  (import "env" "set_anyref" (func $set_anyref (param i32 i32 anyref) (result anyref)))
+ (import "env" "get_exnref" (func $get_exnref (param i32 i32 exnref) (result exnref)))
  (import "env" "set_exnref" (func $set_exnref (param i32 i32 exnref) (result exnref)))
  (func $A (; 12 ;) (type $FUNCSIG$v)
   (local $x i32)