Verify/repair support v850/rx/rl78

[ckormanyos]

The targets v850/rx/rl78 have (or may have) fallen into disarray and have not run on a physical target in quite some time.

This issue tracks any potentially needed verify/repair of those target configurations on actual physical boards.

[ckormanyos]

99cc0f5 gets a v850es/fx2 board up and running (verified) on an F-Line Drive It board using GCC 11.2 for v850-unkown-elf as found in the real-time-cpp-toolchains repository.

[ckormanyos]

Linker problem is observed in target v850es_fx2 when using floating-point mathematical functions.