The powerpc[64le] arch uses different ioctls for custom baud setting: It
uses the old TCSETS*, TCGETS ioctls, not the new TCSETS*2, TCGETS2 ones.
Cross-compiles cleanly, not tested (no h/w currently available).
Uses the "termios2" linux-kernel interface (ioctls TCGETS2, TCSETS2,
TCSETSF2, etc) to provide termios(3)-like functions that allow setting
custom baud rates.
Only works for Linux.