Implement LLVM version of jni_compiler to pass 17 jni_compiler tests.

Because we now have both shadow_frame and sirt (which is just for SirtRef<>
in the LLVM version), we define a new function NumStackReferences() as follows:
  NumStackReferences() = NumSirtReferences() + NumShadowFrameReferences().

(cherry picked from commit 18fe89a14d212da9ec6841f4d19d08482a9610b7)

Change-Id: Idd95ee4276801b1555be87934cd9c4f33ab8a88a
diff --git a/src/jni_internal.cc b/src/jni_internal.cc
index f0943a7..00667ad 100644
--- a/src/jni_internal.cc
+++ b/src/jni_internal.cc
@@ -2300,7 +2300,7 @@
       return JNIWeakGlobalRefType;
     case kSirtOrInvalid:
       // Is it in a stack IRT?
-      if (ts.Self()->SirtContains(java_object)) {
+      if (ts.Self()->StackReferencesContain(java_object)) {
         return JNILocalRefType;
       }