Similar to 806761a7629df268c8aed49657aeccffa6bca449
-mtriple= specifies the full target triple while -march= merely sets the
architecture part of the default target triple (e.g. Windows, macOS),
leaving a target triple which may not make sense.
Therefore, -march= is error-prone and not recommended for tests without
a target triple. The issue has been benign as we recognize
nvptx{,64}-apple-darwin as ELF instead of rejecting it outrightly.
Some generic tests are not supported by the nvptx now. Moreover, they
are no plans to fix the tested features in nvptx. So, suggest to mark
them as UNSUPPORTED
Differential Revision: https://reviews.llvm.org/D123928
