PR tree-optimization/88775
	* include/bits/stl_function.h (greater<_Tp*>::operator(),
	less<_Tp*>::operator(), greater_equal<_Tp*>::operator(),
	less_equal<_Tp*>::operator()): Use __builtin_is_constant_evaluated
	instead of __builtin_constant_p if available.  Don't bother with
	the pointer comparison in C++11 and earlier.

From-SVN: r267800