Code cleanup to improve readablity. Semantics unaffected.

2019-08-21  Piotr Trojanek  <trojanek@adacore.com>

gcc/ada/

	* exp_util.adb (Corresponding_Runtime_Package): Use high-level
	Is_Protected_Type.
	* sem_ch8.adb (Analyze_Renamed_Entry): Likewise.
	* sem_ch9.adb (Analyze_Requeue): Likewise.

From-SVN: r274777