[clang][driver] Rename DriverOption as NoXarchOption (NFC)
As discussed in , ClangFlags::DriverOption is currently only used to
mark options that should not be forwarded to other tools via -Xarch
options. This patch renames this flag accordingly and updates the
corresponding driver diagnostic.
A comment in ToolChain::TranslateXarchArgs is also updated to reflect
the change. The original comment referred to isDriverOption(), which is
no longer available.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D89799