ART: Extract JNI macro assembler for arm64

Extract the JNI assembler parts from the regular assembler.

Change-Id: I0b0ad32e18f585b75e9da0237afe082c25a1d291
Test: m test-art-target (N9)
diff --git a/compiler/Android.mk b/compiler/Android.mk
index 16a158c..d6ddd86 100644
--- a/compiler/Android.mk
+++ b/compiler/Android.mk
@@ -114,6 +114,7 @@
 	optimizing/instruction_simplifier_shared.cc \
 	optimizing/intrinsics_arm64.cc \
 	utils/arm64/assembler_arm64.cc \
+	utils/arm64/jni_macro_assembler_arm64.cc \
 	utils/arm64/managed_register_arm64.cc \
 
 LIBART_COMPILER_SRC_FILES_mips := \