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/compiler_llvm/art_module.ll b/src/compiler_llvm/art_module.ll
index 78d388b..8eb1783 100644
--- a/src/compiler_llvm/art_module.ll
+++ b/src/compiler_llvm/art_module.ll
@@ -130,6 +130,9 @@
                                                      %JavaObject*,
                                                      %JavaObject*)
 
+declare %JavaObject* @art_decode_jobject_in_thread(%JavaObject*,
+                                                   %JavaObject*)
+
 
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 ; RTTI