Similar to previous migration done for other targets (PowerPC, X86, ARM,
etc). Switch from the confusing VariantKind to Specifier, which aligns
with Arm and IBM AIX's documentation.
In addition, rename *MCExpr::getKind, which confusingly shadows the base class getKind.
In the future, relocation specifiers should be encoded as part of
SystemZMCExpr instead of MCSymbolRefExpr.
Some fixes for style issues pointed out by clang-tidy:
- Upper case/lower case fixes
- No else after return
- Removed unused #include's
- Added NOLINTNEXTLINE() for the LLVM* functions
All changes are NFC.
Set ups the infrastructure to create an empty GOFF file.
Also adds a GOFF writer which writes only HDR/END records.
Reviewed By: jhenderson, kpn
Differential Revision: https://reviews.llvm.org/D111437
