It turns out, this breaks only when compiling with both uClibc-ng and
uClibc++. If the libc or libc++ gets swapped out, it compiles fine.

libstdcpp is fine because it already undefs these macros. The actual
bug is probably in uClibc-ng but this is a fine workaround.

Signed-off-by: Rosen Penev <rosenp@gmail.com>