AArch64: Add initial support for AArch64

This is the first patch out of a series of patches that add support for
AArch64, the new 64bit execution state of the ARMv8 Architecture. The
patches add support for LP64 programming model.

The patch adds:
* "arch-aarch64" to the architecture directories.
* "arch-aarch64/include" - headers used by libc
* "arch-aarch64/bionic":
    - crtbegin, crtend support;
    - aarch64 specific syscall stubs;
    - setjmp, clone, vfork assembly files.

Change-Id: If72b859f81928d03ad05d4ccfcb54c2f5dbf99a5
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
diff --git a/libc/arch-aarch64/include/machine/endian.h b/libc/arch-aarch64/include/machine/endian.h
new file mode 100644
index 0000000..87a038d
--- /dev/null
+++ b/libc/arch-aarch64/include/machine/endian.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (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 _AARCH64_ENDIAN_H_
+#define _AARCH64_ENDIAN_H_
+
+#include <sys/types.h>
+#include <sys/endian.h>
+
+#ifdef __GNUC__
+
+#define __swap16md(x) ({                                        \
+    register u_int16_t _x = (x);                                \
+    __asm volatile ("rev16 %0, %0" : "+r" (_x));                \
+    _x;                                                         \
+})
+
+/* Use GCC builtins */
+#define __swap32md(x) __builtin_bswap32(x)
+#define __swap64md(x) __builtin_bswap64(x)
+
+/* Tell sys/endian.h we have MD variants of the swap macros.  */
+#define MD_SWAP
+
+#endif  /* __GNUC__ */
+
+#if defined(__AARCH64EB__)
+#define _BYTE_ORDER _BIG_ENDIAN
+#else
+#define _BYTE_ORDER _LITTLE_ENDIAN
+#endif
+
+#endif /* _AARCH64_ENDIAN_H_ */