The compiler prematurely freezes a private type that is the type of a
formal parameter of an expression function declared within a nested,
inactivated Ghost package, resulting is an error complaining that the
private type must be fully defined at that point. This is fixed by
testing for Ignored_Ghost_Entity in the condition guarding the code that
performs Mask_Unfrozen_Types for an expression function without a
separate declaration, ensuring that the expression function's profile
isn't frozen prematurely.

2019-07-04  Gary Dismukes  <dismukes@adacore.com>

gcc/ada/

	* sem_ch6.adb (Analyze_Subprogram_Body_Helper): The special
	treatment of calling Mask_Unfrozen_Types must also be done in
	the case of an Ignored_Ghost_Entity, because Expander_Active is
	False in that case.

gcc/testsuite/

	* gnat.dg/ghost5.adb, gnat.dg/ghost5.ads,
	gnat.dg/ghost5_parent.ads: New testcase.

From-SVN: r273065