Remove \brief commands from doxygen comments.

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

Differential Revision: https://reviews.llvm.org/D46290

llvm-svn: 331272
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 1be16c5..2cf2d27 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1824,7 +1824,7 @@
   return Changed;
 }
 
-/// \brief Determine if we can hoist sink a sole store instruction out of a
+/// Determine if we can hoist sink a sole store instruction out of a
 /// conditional block.
 ///
 /// We are looking for code like the following:
@@ -1885,7 +1885,7 @@
   return nullptr;
 }
 
-/// \brief Speculate a conditional basic block flattening the CFG.
+/// Speculate a conditional basic block flattening the CFG.
 ///
 /// Note that this is a very risky transform currently. Speculating
 /// instructions like this is most often not desirable. Instead, there is an MI