Remove @brief commands from doxygen comments, too.

This is a follow-up to r331272.

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

https://reviews.llvm.org/D46290

llvm-svn: 331275
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 21a0042..e486890 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -2081,7 +2081,7 @@
 /// # bitcast i32* %x to i8*
 /// # bitcast <2 x i32> %x to <4 x i16> 
 /// # ptrtoint i32* %x to i32     ; on 32-bit plaforms only
-/// @brief Determine if the described cast is a no-op.
+/// Determine if the described cast is a no-op.
 bool CastInst::isNoopCast(Instruction::CastOps Opcode,
                           Type *SrcTy,
                           Type *DestTy,
@@ -2449,7 +2449,7 @@
   return CreatePointerBitCastOrAddrSpaceCast(S, Ty, Name, InsertAtEnd);
 }
 
-/// @brief Create a BitCast or a PtrToInt cast instruction
+/// Create a BitCast or a PtrToInt cast instruction
 CastInst *CastInst::CreatePointerCast(Value *S, Type *Ty,
                                       const Twine &Name,
                                       Instruction *InsertBefore) {