Fix some cases where StringRef was being passed by const reference. Remove const from some other StringRefs since its implicitly const already.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216820 91177308-0d34-0410-b5e6-96231b3b80d8
Add a test for converting ArrayRef<T *> to ArrayRef<const T *>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216821 91177308-0d34-0410-b5e6-96231b3b80d8
Use StringRef to avoid copies and simplify code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216822 91177308-0d34-0410-b5e6-96231b3b80d8
Remove 'virtual' keyword from methods markedwith 'override' keyword.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216823 91177308-0d34-0410-b5e6-96231b3b80d8
Teach llvm-bcanalyzer to use one stream's BLOCKINFO to read another stream.

This allows streams that only use BLOCKINFO for debugging purposes to omit
the block entirely. As long as another stream is available with the correct
BLOCKINFO, the first stream can still be analyzed and dumped.

As part of this commit, BitstreamReader gets a move constructor and move
assignment operator, as well as a takeBlockInfo method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216826 91177308-0d34-0410-b5e6-96231b3b80d8