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/Format/FormatInternal.h b/clang/lib/Format/FormatInternal.h
index 3984158..5c59e76 100644
--- a/clang/lib/Format/FormatInternal.h
+++ b/clang/lib/Format/FormatInternal.h
@@ -8,7 +8,7 @@
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// \brief This file declares Format APIs to be used internally by the
+/// This file declares Format APIs to be used internally by the
 /// formatting library implementation.
 ///
 //===----------------------------------------------------------------------===//
@@ -24,7 +24,7 @@
 namespace format {
 namespace internal {
 
-/// \brief Reformats the given \p Ranges in the code fragment \p Code.
+/// Reformats the given \p Ranges in the code fragment \p Code.
 ///
 /// A fragment of code could conceptually be surrounded by other code that might
 /// constrain how that fragment is laid out.