Added PKG_USE_MIPS16 as it seems not to build under mipsel.

Error: opcode not supported on this processor: mips32r2 (mips32r2) `sync'

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

The spoofer client is part of a system to measure the Internet's resistance
to packets with a spoofed (forged) source IP address.

Signed-off-by: Ken Keys <kkeys@caida.org>