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/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index 94490bd..358103d 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -333,7 +333,7 @@
   return CurSubmoduleState->Macros.end();
 }
 
-/// \brief Compares macro tokens with a specified token value sequence.
+/// Compares macro tokens with a specified token value sequence.
 static bool MacroDefinitionEquals(const MacroInfo *MI,
                                   ArrayRef<TokenValue> Tokens) {
   return Tokens.size() == MI->getNumTokens() &&
@@ -645,7 +645,7 @@
     Diag(Identifier,it->second) << Identifier.getIdentifierInfo();
 }
 
-/// \brief Returns a diagnostic message kind for reporting a future keyword as
+/// Returns a diagnostic message kind for reporting a future keyword as
 /// appropriate for the identifier and specified language.
 static diag::kind getFutureCompatDiagKind(const IdentifierInfo &II,
                                           const LangOptions &LangOpts) {
@@ -805,7 +805,7 @@
   LastTokenWasAt = Result.is(tok::at);
 }
 
-/// \brief Lex a token following the 'import' contextual keyword.
+/// Lex a token following the 'import' contextual keyword.
 ///
 void Preprocessor::LexAfterModuleImport(Token &Result) {
   // Figure out what kind of lexer we actually have.