px4_io - add knob to ensure ARCH_MATH_H is kept
Upstream changes added ARCH_HAVE_MATH_H to protect from archs
without math.h from causing isses for users setting
CONFIG_ARCH_MATH_H and getting errors. PX4 provides a math.h
and we need CONFIG_ARCH_MATH_H set. So this Selects
ARCH_HAVE_MATH_H perserving CONFIG_ARCH_MATH_H a defconfig