[SystemZ][z/OS] Add GOFF support to file magic identification

- This patch adds in the GOFF format to the file magic identification logic in LLVM
- Currently, for the object file support, GOFF is marked as having as an error
- However, this is only temporary until https://reviews.llvm.org/D98437 is merged in

Reviewed By: abhina.sreeskantharajan

Differential Revision: https://reviews.llvm.org/D105993