We use DWARF 5 on Fuchsia, make it the toolchain default.
We aren't actually using DWARF 5 yet AFAICT. Our builds don't pass -gdwarf-5. So I'm not sure we have yet verified that all the DWARF-consuming tools people are using with Fuchsia binaries can handle all of DWARF 5 (which has several major format changes). I'd certainly like 5 to be the default, but I think we need to establish a set of consumers we care about and verify their format version support before we can be sure about this.