Doxygenize the documentation comments

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index 33a914da9535ce25ba926491856e56318d488fa9..671bab029d0d30871a55e94f9a27052f27f36a9d 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -6,13 +6,14 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This file implements the skeleton of the TargetLowering class,
-// specifically invoking the appropriate lowering method for a given
-// instruction kind and driving global register allocation.  It also
-// implements the non-deleted instruction iteration in
-// LoweringContext.
-//
+///
+/// \file
+/// This file implements the skeleton of the TargetLowering class,
+/// specifically invoking the appropriate lowering method for a given
+/// instruction kind and driving global register allocation.  It also
+/// implements the non-deleted instruction iteration in
+/// LoweringContext.
+///
 //===----------------------------------------------------------------------===//
 
 #include "IceTargetLowering.h"