[ARM] Work around Clang 9 after MCCFIInstruction::OpType uses uint8_t
ARMAsmBackend.cpp:1205:57: error: use of overloaded operator '<<' is ambiguous (with operand types 'llvm::raw_ostream' and
'llvm::MCCFIInstruction::OpType')
"unwind encoding, opcode=" << Inst.getOperation()
~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~