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/Parse/ParseTentative.cpp b/clang/lib/Parse/ParseTentative.cpp
index 17ff9f9..dbc8d55 100644
--- a/clang/lib/Parse/ParseTentative.cpp
+++ b/clang/lib/Parse/ParseTentative.cpp
@@ -401,7 +401,7 @@
   }
 };
 
-/// \brief Disambiguates between a declaration in a condition, a
+/// Disambiguates between a declaration in a condition, a
 /// simple-declaration in an init-statement, and an expression for
 /// a condition of a if/switch statement.
 ///
@@ -472,7 +472,7 @@
     return ConditionOrInitStatement::Expression;
 }
 
-  /// \brief Determine whether the next set of tokens contains a type-id.
+  /// Determine whether the next set of tokens contains a type-id.
   ///
   /// The context parameter states what context we're parsing right
   /// now, which affects how this routine copes with the token
@@ -553,7 +553,7 @@
   return TPR == TPResult::True;
 }
 
-/// \brief Returns true if this is a C++11 attribute-specifier. Per
+/// Returns true if this is a C++11 attribute-specifier. Per
 /// C++11 [dcl.attr.grammar]p6, two consecutive left square bracket tokens
 /// always introduce an attribute. In Objective-C++11, this rule does not
 /// apply if either '[' begins a message-send.