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/Target/AMDGPU/SIShrinkInstructions.cpp b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
index 61cbba4..33fd5a3 100644
--- a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -126,7 +126,7 @@
          !TII->hasModifiersSet(MI, AMDGPU::OpName::clamp);
 }
 
-/// \brief This function checks \p MI for operands defined by a move immediate
+/// This function checks \p MI for operands defined by a move immediate
 /// instruction and then folds the literal constant into the instruction if it
 /// can. This function assumes that \p MI is a VOP1, VOP2, or VOPC instructions.
 static bool foldImmediates(MachineInstr &MI, const SIInstrInfo *TII,