There are two problems here; first that the emitted asm for
-fdebug-types-section is ELF-specfic leading to assembler errors for
Mach-O. If we fix this, we get a secondary fail since the debug linker
does not recognise DW_FORM_ref_sig8. Disable ths test until we get
DWARF-5 support in the external Darwin toolchain components.