build: add basic arm64 support

This commit adds basic arm64 support to the build.  Building the bundled
openssl is disabled pending an upgrade to openssl 1.2, the currently
bundled version has some hand-rolled assembly that is 32 bits only.

PR-URL: https://github.com/iojs/io.js/pull/1028
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: Rod Vagg <rod@vagg.org>

configure

@@ -38,7 +38,8 @@ parser.add_option('--debug',
 parser.add_option('--dest-cpu',
     action='store',
     dest='dest_cpu',
-    help='CPU architecture to build for. Valid values are: arm, ia32, x32, x64')
+    help='CPU architecture to build for. '
+         'Valid values are: arm, arm64, ia32, x32, x64')
 
 parser.add_option('--dest-os',
     action='store',
@@ -436,10 +437,11 @@ def host_arch_cc():
   k = cc_macros()
 
   matchup = {
-    '__x86_64__'  : 'x64',
+    '__aarch64__' : 'arm64',
-    '__i386__'    : 'ia32',
     '__arm__'     : 'arm',
+    '__i386__'    : 'ia32',
     '__mips__'    : 'mips',
+    '__x86_64__'  : 'x64',
   }
 
   rtn = 'ia32' # default
@@ -510,6 +512,13 @@ def configure_node(o):
 
   if target_arch == 'arm':
     configure_arm(o)
+  elif (target_arch == 'arm64' and
+        not options.shared_openssl and
+        not options.without_ssl):
+    # FIXME(bnoordhuis) It's not possible to build the bundled openssl due to
+    # deps/openssl/asm/arm-elf-gas/modes/ghash-armv4.S, which is 32 bits only.
+    warn('not building openssl, arm64 not yet supported')
+    options.without_ssl = True
 
   if flavor in ('solaris', 'mac', 'linux', 'freebsd'):
     use_dtrace = not options.without_dtrace

deps/openssl/config/opensslconf.h

@@ -190,7 +190,7 @@
    * boundary. See crypto/rc4/rc4_enc.c for further details.
    */
 # undef RC4_CHUNK
-# if defined(_M_X64) || defined(__x86_64__)
+# if defined(_M_X64) || defined(__aarch64__) || defined(__x86_64__)
 #  define RC4_CHUNK unsigned long long
 # elif defined(__arm__)
 #  define RC4_CHUNK unsigned long
@@ -220,7 +220,7 @@
 # undef THIRTY_TWO_BIT
 # undef SIXTEEN_BIT
 # undef EIGHT_BIT
-# if defined(_M_X64) || defined(__x86_64__)
+# if defined(_M_X64) || defined(__aarch64__) || defined(__x86_64__)
 #  if defined(_LP64)
 #   define SIXTY_FOUR_BIT_LONG
 #  else