Doxygenize the documentation comments

src/IceConditionCodesX8664.h

Index: src/IceConditionCodesX8664.h
diff --git a/src/IceConditionCodesX8664.h b/src/IceConditionCodesX8664.h
index 297b54b5ac0d3b82ce26f3e58f855fe2158b50c9..ba94617bf0e8e3a908f9782be8146db95f866c5a 100644
--- a/src/IceConditionCodesX8664.h
+++ b/src/IceConditionCodesX8664.h
@@ -6,9 +6,10 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This file declares the condition codes for x86-64.
-//
+///
+/// \file
+/// This file declares the condition codes for x86-64.
+///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICECONDITIONCODESX8664_H
@@ -20,8 +21,8 @@
 namespace Ice {
 
 namespace CondX8664  {
-// An enum of condition codes used for branches and cmov. The enum value
-// should match the value used to encode operands in binary instructions.
+/// An enum of condition codes used for branches and cmov. The enum value
+/// should match the value used to encode operands in binary instructions.
 enum BrCond {
 #define X(tag, encode, opp, dump, emit) tag encode,
     ICEINSTX8664BR_TABLE
@@ -29,9 +30,9 @@ enum BrCond {
     Br_None
 };
 
-// An enum of condition codes relevant to the CMPPS instruction. The enum
-// value should match the value used to encode operands in binary
-// instructions.
+/// An enum of condition codes relevant to the CMPPS instruction. The enum
+/// value should match the value used to encode operands in binary
+/// instructions.
 enum CmppsCond {
 #define X(tag, emit) tag,
     ICEINSTX8664CMPPS_TABLE