__gnu_h2f_ieee and __gnu_f2h_ieee are introduce by ARM and set that as
default name for fp16 and fp32 conversion in LLVM.
However RISC-V GCC using default naming scheme for that, which is
__extendhfsf2 and __truncsfhf2 for that, that cause runtime ABI
incompatible issue.
Although we didn't have formal runtime ABI spec to specify those naming
convention yet, but I think it would be great to fix the incompatible
issue first.
And I've plan to create a runtime ABI spec undere psABI spec this year.