Remove the now unused StringRefMemoryObject.h.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221755 91177308-0d34-0410-b5e6-96231b3b80d8
Use a function_ref now that it works (r221753).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221756 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused method. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221757 91177308-0d34-0410-b5e6-96231b3b80d8
Make readBytes pure virtual. Every real implementation has it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221758 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused method. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221759 91177308-0d34-0410-b5e6-96231b3b80d8