Move object construction into [] so the temporary can be moved.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183075 91177308-0d34-0410-b5e6-96231b3b80d8
Move getRealLinkageName to a common place and remove all the duplicates of it.

Also simplify code a bit while there. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183076 91177308-0d34-0410-b5e6-96231b3b80d8