linking: remove check for target_supports_libunwind

I'm not sure why this was ever there. Maybe it was working around a
problem with LLVM 9. Anyway this fixes linking C++ code for 32 bit
arm and riscv.
6408766d6bAndrew Kelley committed on 3/30/2020, 7:50:53 PMparent9e7ae06
3 files changedLine totals unavailable