duplicate symbol '_bitbang_swd'

[Fabian]

Building on macOS yields the following error:

duplicate symbol '_bitbang_swd' in:
    src/.libs/libopenocd.a(libocdjtagdrivers_la-remote_bitbang.o)
    src/.libs/libopenocd.a(libocdjtagdrivers_la-bitbang.o)
ld: 1 duplicate symbol for architecture x86_64
collect2: error: ld returned 1 exit status
make[2]: *** [src/openocd] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

Updating riscv-openocd solves this issue, but introduces new ones.