ada: Minor consistency tweaks in Sem_Ch4

ada: Minor consistency tweaks in Sem_Ch4

This ensures that, during the analysis of the qualified expressions, type
conversions and unchecked type conversions, the determination of the type
of the node and the analysis of its expression are done in the same order.

No functional changes.

gcc/ada/

	* sem_ch4.adb (Analyze_Qualified_Expression): Analyze the
	expression only after setting the type.
	(Analyze_Unchecked_Type_Conversion): Likewise.
	(Analyze_Short_Circuit): Likewise for the operands.
	(Analyze_Type_Conversion): Minor tweaks.
	(Analyze_Unchecked_Expression): Likewise.