Remove \brief commands from doxygen comments.

This is similar to the LLVM change https://reviews.llvm.org/D46290.

We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by

for i in $(git grep -l '\@brief'); do perl -pi -e 's/\@brief //g' $i & done
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done

Differential Revision: https://reviews.llvm.org/D46320

llvm-svn: 331834
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 5cd7717..a692bab 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -658,7 +658,7 @@
 
   ~ApplyDebugLocation();
 
-  /// \brief Apply TemporaryLocation if it is valid. Otherwise switch
+  /// Apply TemporaryLocation if it is valid. Otherwise switch
   /// to an artificial debug location that has a valid scope, but no
   /// line information.
   ///
@@ -672,7 +672,7 @@
   static ApplyDebugLocation CreateArtificial(CodeGenFunction &CGF) {
     return ApplyDebugLocation(CGF, false, SourceLocation());
   }
-  /// \brief Apply TemporaryLocation if it is valid. Otherwise switch
+  /// Apply TemporaryLocation if it is valid. Otherwise switch
   /// to an artificial debug location that has a valid scope, but no
   /// line information.
   static ApplyDebugLocation