tcg/aarch64: Implement goto_ptr

tcg/aarch64: Implement goto_ptr

Measurements:

                      SPECint06 (test set), x86_64-linux-user. Host: APM 64-bit ARMv8 (Atlas/A57) @ 2.4 GHz

 1.45x +-+-------------------------------------------------------------------------------------------------------------+-+
       |                                      *****                                                                      |
       |      +++                             *   *                                                    +goto-ptr         |
  1.4x +-+...*****............................*...*....................................................................+-+
       |     *+++*                            *   *                            +++                                       |
 1.35x +-+...*...*............................*...*...........................*****....................................+-+
       |     *   *                            *   *                           *+++*                                      |
       |     *   *                            *   *                           *   *                                      |
  1.3x +-+...*...*............................*...*...........................*...*....................................+-+
       |     *   *                            *   *                           *   *                                      |
       |     *   *                            *   *                           *   *                    *****             |
 1.25x +-+...*...*...........*****............*...*...........................*...*............*****...*...*...........+-+
       |     *   *           *   *            *   *                           *   *            *+++*   *   *             |
  1.2x +-+...*...*...........*...*............*...*...........................*...*............*...*...*...*...........+-+
       |     *   *           *   *            *   *                           *   *            *   *   *   *             |
       |     *   *           *   *            *   *                           *   *            *   *   *   *   *****     |
 1.15x +-+...*...*...........*...*............*...*...........................*...*............*...*...*...*...*...*...+-+
       |     *   *           *   *            *   *                           *   *    +++     *   *   *   *   *   *     |
       |     *   *           *   *            *   *                           *   *   *****    *   *   *   *   *   *     |
  1.1x +-+...*...*...........*...*....*****...*...*...*****...................*...*...*...*....*...*...*...*...*...*...+-+
       |     *   *           *   *    *   *   *   *   *   *                   *   *   *   *    *   *   *   *   *   *     |
 1.05x +-+...*...*...........*...*....*...*...*...*...*...*...................*...*...*...*....*...*...*...*...*...*...+-+
       |     *   *   *****   *   *    *   *   *   *   *   *                   *   *   *   *    *   *   *   *   *   *     |
       |     *   *   *   *   *   *    *   *   *   *   *   *   *****   *****   *   *   *   *    *   *   *   *   *   *     |
    1x +-+---*****---*****---*****----*****---*****---*****---*****---*****---*****---*****----*****---*****---*****---+-+
          astar   bzip2     gcc    gobmk h264ref   hmmlibquantum     mcf omnetpperlbench    sjenxalancbmk   hmean
  png: http://imgur.com/en9HE8L

Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>