Add to the VexAbiInfo structure, two new fields:
  guest_amd64_assume_fs_is_zero
  guest_amd64_assume_gs_is_0x60

and use them to properly enable %fs/%gs prefix decoding for
guest-amd64.  This is needed to support amd64-darwin cleanly.

Unfortunately the VexAbiInfo needs to be plumbed to every single where
an address is decoded, which means the patch is vast, although very
trivial.



git-svn-id: svn://svn.valgrind.org/vex/trunk@1875 8f6e269a-dfd6-0310-a8e1-e2731360e62c
diff --git a/priv/main/vex_main.c b/priv/main/vex_main.c
index 07e2943..6586304 100644
--- a/priv/main/vex_main.c
+++ b/priv/main/vex_main.c
@@ -717,6 +717,8 @@
 void LibVEX_default_VexAbiInfo ( /*OUT*/VexAbiInfo* vbi )
 {
    vbi->guest_stack_redzone_size       = 0;
+   vbi->guest_amd64_assume_fs_is_zero  = False;
+   vbi->guest_amd64_assume_gs_is_0x60  = False;
    vbi->guest_ppc_zap_RZ_at_blr        = False;
    vbi->guest_ppc_zap_RZ_at_bl         = NULL;
    vbi->guest_ppc_sc_continues_at_LR   = False;