nlpt-select: Fix for compile error on some platforms.
nlpt-select: Fix for compile error on some platforms.

abtink/wpantund,openthread/wpantund,aeliot/wpantund,d-bahr/wpantund,d-bahr/wpantund,abtink/wpantund,aeliot/wpantund,aeliot/wpantund,d-bahr/wpantund,aeliot/wpantund,abtink/wpantund,abtink/wpantund,openthread/wpantund,openthread/wpantund,d-bahr/wpantund,openthread/wpantund