918f6f581d
This new opcode was initially documented as "pac_sign_return_address" in https://github.com/MicrosoftDocs/cpp-docs/pull/4202, but was soon afterwards renamed into "pac_sign_lr" in https://github.com/MicrosoftDocs/cpp-docs/pull/4209, as the other name was unwieldy, and there were no other external references to that name anywhere. Rename our external .seh assembler directive - it hasn't been merged for very long yet, so there's probably no external use to account for. Rename all other internal references to the opcode similarly. Differential Revision: https://reviews.llvm.org/D135762