The upstream code has problems. They use a specific toolchain to mitigate
the problems.

I couldn't get it to run properly on NetBSD amd64, with clang or gcc5.

According to upstream it depends on gcc 4.8, which works on amd64 and ARM.

gcc 4.9 also works on ARM.

(This has always been a problem in libretro-picodrive, and isn't specific
to this newer version.)
