Add tzcnt as an acceptable instruction to x86-64 validator (it already

src/trusted/validator/x86/decoder/gen/ncopcode_insts.h

Index: src/trusted/validator/x86/decoder/gen/ncopcode_insts.h
===================================================================
--- src/trusted/validator/x86/decoder/gen/ncopcode_insts.h	(revision 9237)
+++ src/trusted/validator/x86/decoder/gen/ncopcode_insts.h	(working copy)
@@ -608,28 +608,29 @@
   InstSysexit = 593,
   InstSysret = 594,
   InstTest = 595,
-  InstUcomisd = 596,
-  InstUcomiss = 597,
-  InstUd2 = 598,
-  InstUnpckhpd = 599,
-  InstUnpckhps = 600,
-  InstUnpcklpd = 601,
-  InstUnpcklps = 602,
-  InstVerr = 603,
-  InstVerw = 604,
-  InstVmload = 605,
-  InstVmmcall = 606,
-  InstVmrun = 607,
-  InstVmsave = 608,
-  InstWbinvd = 609,
-  InstWrmsr = 610,
-  InstXadd = 611,
-  InstXchg = 612,
-  InstXlat = 613,
-  InstXor = 614,
-  InstXorpd = 615,
-  InstXorps = 616,
-  NaClMnemonicEnumSize = 617, /* special size marker */
+  InstTzcnt = 596,
+  InstUcomisd = 597,
+  InstUcomiss = 598,
+  InstUd2 = 599,
+  InstUnpckhpd = 600,
+  InstUnpckhps = 601,
+  InstUnpcklpd = 602,
+  InstUnpcklps = 603,
+  InstVerr = 604,
+  InstVerw = 605,
+  InstVmload = 606,
+  InstVmmcall = 607,
+  InstVmrun = 608,
+  InstVmsave = 609,
+  InstWbinvd = 610,
+  InstWrmsr = 611,
+  InstXadd = 612,
+  InstXchg = 613,
+  InstXlat = 614,
+  InstXor = 615,
+  InstXorpd = 616,
+  InstXorps = 617,
+  NaClMnemonicEnumSize = 618, /* special size marker */
 } NaClMnemonic;
 
 /* Returns the name of an NaClMnemonic constant. */