Avoid loading an undefined value in the ranger_cache constructor.

Avoid loading an undefined value in the ranger_cache constructor.

Enable_new_values takes a boolean, returning the old value.  The constructor
for ranger_cache initialized the m_new_value_p field by calling this routine
and ignorng the result.  This potentially loads the old value uninitialized.

	* gimple-range-cache.cc (ranger_cache::ranger_cache): Initialize
	m_new_value_p directly.