ada: Fix internal error on ambiguous operands of comparison operator

ada: Fix internal error on ambiguous operands of comparison operator

This is a regression introduced when the diagnosis of ambiguous operands
for comparison and equality operators was moved from the analysis to the
resolution phase in order to avoid spurious ambiguities in specific cases.

When an ambiguity is detected for the operands of predefined comparison
and equality operators during analysis, it needs to be recorded so that
later calls to the disambiguation routine know about this ambiguity for
the case where the context has been resolved to boolean.

gcc/ada/ChangeLog:

	* sem_type.ads (Interp ): Add Opnd_Typ component and remove default
	value for Abstract_Op component.
	(Add_One_Interp): Rename Opnd_Type parameter to Opnd_Typ.
	* sem_type.adb (Add_One_Interp): Likewise.
	(Add_One_Interp.Add_Entry): Record the operand type as well.
	(Collect_Interp): Record Empty for the operand type.
	(Disambiguate.Is_Ambiguous_Boolean_Operator): New predicate.
	(Disambiguate): Use it to detect recorded ambiguity cases.
	* sem_ch4.adb (Find_Comparison_Equality_Types): Add commentary.