test_split_dwarf_object_generate_output_dir_changes fails with "clang: error: -gsplit-dwarf is unsupported with RISC-V linker relaxation (-mrelax)"

[nc7s]

.. as can be seen in Debian buildd logs.

sccache currently does not seem to support the -m{no-,}relax pair of flags for clang, so even patching the test to add -mno-relax does not work. For now I'll have to patch the test out for riscv64.

[sylvestre]

Don't hesitate to propose a PR :)