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/CodeGen/AsmPrinter/AddressPool.h b/llvm/lib/CodeGen/AsmPrinter/AddressPool.h
index 990a158..5350006 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AddressPool.h
+++ b/llvm/lib/CodeGen/AsmPrinter/AddressPool.h
@@ -39,7 +39,7 @@
 public:
   AddressPool() = default;
 
-  /// \brief Returns the index into the address pool with the given
+  /// Returns the index into the address pool with the given
   /// label/symbol.
   unsigned getIndex(const MCSymbol *Sym, bool TLS = false);