A64: Fix some compile errors when building for Android.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index b960d100e96e0005a58a242ba1935e6d31101af9..f3829b08efc138c88d03c1ec368820a05faa8435 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1806,7 +1806,7 @@ Isolate::Isolate()
   thread_manager_->isolate_ = this;
 
 #if V8_TARGET_ARCH_ARM && !defined(__arm__) || \
-    V8_TARGET_ARCH_A64 && !defined(__arm__) || \
+    V8_TARGET_ARCH_A64 && !defined(__aarch64__) || \
     V8_TARGET_ARCH_MIPS && !defined(__mips__)
   simulator_initialized_ = false;
   simulator_i_cache_ = NULL;