fix doxygen brief in subzero header files

src/IceTargetLoweringX8632.h

Index: src/IceTargetLoweringX8632.h
diff --git a/src/IceTargetLoweringX8632.h b/src/IceTargetLoweringX8632.h
index b1d74f57573d1549bcfa3ab2649674c071033506..d2c36e957e53d37994253f03fa3dad64ad5939af 100644
--- a/src/IceTargetLoweringX8632.h
+++ b/src/IceTargetLoweringX8632.h
@@ -8,7 +8,7 @@
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// This file declares the TargetLoweringX8632 class, which implements the
+/// \brief Declares the TargetLoweringX8632 class, which implements the
 /// TargetLowering interface for the x86-32 architecture.
 ///
 //===----------------------------------------------------------------------===//