fix doxygen brief in subzero header files

src/IceDefs.h

 //===- subzero/src/IceDefs.h - Common Subzero declarations ------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// This file declares various useful types and classes that have widespread use
-/// across Subzero. Every Subzero source file is expected to include IceDefs.h.
+/// \brief Declares various useful types and classes that have widespread use
+/// across Subzero.
+///
+/// Every Subzero source file is expected to include IceDefs.h.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEDEFS_H
 #define SUBZERO_SRC_ICEDEFS_H
 
 #include "IceBuildDefs.h" // TODO(stichnot): move into individual files
 #include "IceTLS.h"
 
 #include "llvm/ADT/ArrayRef.h"
@@ skipping 279 matching lines @@
   RPE_GlobalVariableReordering,
   RPE_NopInsertion,
   RPE_PooledConstantReordering,
   RPE_RegAllocRandomization,
   RPE_num
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEDEFS_H