Rename A64 port to ARM64 port

src/arm64/lithium-arm64.h

Index: src/arm64/lithium-arm64.h
diff --git a/src/a64/lithium-a64.h b/src/arm64/lithium-arm64.h
similarity index 99%
rename from src/a64/lithium-a64.h
rename to src/arm64/lithium-arm64.h
index 1bd1b80dcbd62ca76dd0d6899c0b3e3507947638..da3c5f17b5a7ed757882b4843923e7afa817a97a 100644
--- a/src/a64/lithium-a64.h
+++ b/src/arm64/lithium-arm64.h
@@ -25,8 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef V8_A64_LITHIUM_A64_H_
-#define V8_A64_LITHIUM_A64_H_
+#ifndef V8_ARM64_LITHIUM_ARM64_H_
+#define V8_ARM64_LITHIUM_ARM64_H_
 
 #include "hydrogen.h"
 #include "lithium-allocator.h"
@@ -3018,8 +3018,8 @@ class LChunkBuilder V8_FINAL : public LChunkBuilderBase {
   // register by the instruction implementation.
   //
   // This behaves identically to ARM's UseTempRegister. However, it is renamed
-  // to discourage its use in A64, since in most cases it is better to allocate
-  // a temporary register for the Lithium instruction.
+  // to discourage its use in ARM64, since in most cases it is better to
+  // allocate a temporary register for the Lithium instruction.
   MUST_USE_RESULT LOperand* UseRegisterAndClobber(HValue* value);
 
   // The operand created by UseRegisterAtStart is guaranteed to be live only at
@@ -3097,4 +3097,4 @@ class LChunkBuilder V8_FINAL : public LChunkBuilderBase {
 
 } }  // namespace v8::internal
 
-#endif  // V8_A64_LITHIUM_A64_H_
+#endif  // V8_ARM64_LITHIUM_ARM64_H_