Doxygenize the documentation comments

src/IceTLS.h

 //===- subzero/src/IceTLS.h - thread_local workaround -----------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This file defines macros for working around the lack of support for
-// thread_local in MacOS 10.6.  It assumes std::thread is written in
-// terms of pthread.  Define ICE_THREAD_LOCAL_HACK to enable the
-// pthread workarounds.
-//
+///
+/// \file
+/// This file defines macros for working around the lack of support for
+/// thread_local in MacOS 10.6.  It assumes std::thread is written in
+/// terms of pthread.  Define ICE_THREAD_LOCAL_HACK to enable the
+/// pthread workarounds.
+///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICETLS_H
 #define SUBZERO_SRC_ICETLS_H
 
 #if defined(_MSC_VER)
 #define ICE_ATTRIBUTE_TLS __declspec(thread)
 #else // !_MSC_VER
 #define ICE_ATTRIBUTE_TLS thread_local
 #endif // !_MSC_VER
@@ skipping 66 matching lines @@
   static ICE_ATTRIBUTE_TLS Type FieldName
 #define ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName)                       \
   ICE_ATTRIBUTE_TLS Type ClassName::FieldName = nullptr
 #define ICE_TLS_INIT_FIELD(FieldName)
 #define ICE_TLS_GET_FIELD(FieldName) (FieldName)
 #define ICE_TLS_SET_FIELD(FieldName, Value) (FieldName = (Value))
 
 #endif // !ICE_THREAD_LOCAL_HACK
 
 #endif // SUBZERO_SRC_ICETLS_H