fix Fp::div

include/mcl/operator.hpp

@@ -37,7 +37,7 @@ struct Operator : E {
 	template<class S> MCL_FORCE_INLINE T& operator*=(const S& rhs) { T::mul(static_cast<T&>(*this), static_cast<const T&>(*this), rhs); return static_cast<T&>(*this); }
 	template<class S> friend MCL_FORCE_INLINE T operator*(const T& a, const S& b) { T c; T::mul(c, a, b); return c; }
 	MCL_FORCE_INLINE T& operator/=(const T& rhs) { T c; T::inv(c, rhs); T::mul(static_cast<T&>(*this), static_cast<const T&>(*this), c); return static_cast<T&>(*this); }
-	friend MCL_FORCE_INLINE void div(T& c, const T& a, const T& b) { T t; T::inv(t, b); T::mul(c, a, t); }
+	static MCL_FORCE_INLINE void div(T& c, const T& a, const T& b) { T t; T::inv(t, b); T::mul(c, a, t); }
 	friend MCL_FORCE_INLINE T operator/(const T& a, const T& b) { T c; T::inv(c, b); c *= a; return c; }
 	MCL_FORCE_INLINE T operator-() const { T c; T::neg(c, static_cast<const T&>(*this)); return c; }
 	template<class tag2, size_t maxBitSize2, template<class _tag, size_t _maxBitSize> class FpT>