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/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 0156e75..20874fc 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -395,7 +395,7 @@
   return llvm::Reloc::PIC_;
 }
 
-/// \brief Create a new Regex instance out of the string value in \p RpassArg.
+/// Create a new Regex instance out of the string value in \p RpassArg.
 /// It returns a pointer to the newly generated Regex instance.
 static std::shared_ptr<llvm::Regex>
 GenerateOptimizationRemarkRegex(DiagnosticsEngine &Diags, ArgList &Args,