This simplifies the case if we already have access to the raw data that we need to store in a ConstantDataArray.
The new factor method can also be reused for implementing the factory method that gets the data as ArrayRef.
Differential Revision: https://reviews.llvm.org/D47706
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335028 91177308-0d34-0410-b5e6-96231b3b80d8