Use libvixl to implement disassembly output in debug
logs for A64, for use with both AArch64 hosts and targets.
Signed-off-by: NClaudio Fontana <claudio.fontana@linaro.org>
[PMM:
 * added support for target disassembly
 * switched to custom QEMUDisassembler so the output format
   matches what QEMU expects
 * make sure we correctly fall back to "just print hex"
   if we didn't build the AArch64 disassembler because of
   lack of a C++ compiler
 * rename from 'aarch64' to 'arm-a64' because this is a
   disassembler for the A64 instruction set
 * merge aarch64.c and aarch64-cxx.cc into one C++ file
 * simplify the aarch64.c<->aarch64-cxx.cc interface]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Fix various minor issues with upstream libvixl so that it will compile
successfully on the platforms QEMU cares about:
 * remove unused GBytes constant (it clashes with the glib headers)
 * fix suffixes on constants to use 'LL' for 64 bit constants so
   we can compile on 32 bit hosts
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

Add the subset of the libvixl sources that are needed for the
A64 disassembler support. These sources come from
https://github.com/armvixl/vixl commit 578645f14e122d2b
which is VIXL release 1.1.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>