Transforms: use typedef rather than using aliases

Visual Studio 2012 apparently does not support using alias declarations.  Use
the more traditional typedef approach.  This should let the Windows buildbots
pass.  NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221554 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed