AArch64/ARM64: move ARM64 into AArch64's place

This commit starts with a "git mv ARM64 AArch64" and continues out
from there, renaming the C++ classes, intrinsics, and other
target-local objects for consistency.

"ARM64" test directories are also moved, and tests that began their
life in ARM64 use an arm64 triple, those from AArch64 use an aarch64
triple. Both should be equivalent though.

This finishes the AArch64 merge, and everyone should feel free to
continue committing as normal now.

llvm-svn: 209577
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.h b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.h
new file mode 100644
index 0000000..bc6973b
--- /dev/null
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.h
@@ -0,0 +1,26 @@
+//===-- AArch64ELFStreamer.h - ELF Streamer for AArch64 ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements ELF streamer information for the AArch64 backend.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AARCH64_ELF_STREAMER_H
+#define LLVM_AARCH64_ELF_STREAMER_H
+
+#include "llvm/MC/MCELFStreamer.h"
+
+namespace llvm {
+
+MCELFStreamer *createAArch64ELFStreamer(MCContext &Context, MCAsmBackend &TAB,
+                                        raw_ostream &OS, MCCodeEmitter *Emitter,
+                                        bool RelaxAll, bool NoExecStack);
+}
+
+#endif // AArch64_ELF_STREAMER_H