ada: Improve -gnatyx style check

ada: Improve -gnatyx style check

Check redundant parentheses in many more places, for now only under
-gnatdQ, while pending violations are fixed.

gcc/ada/

	* par-ch3.adb, sem_ch4.adb (P_Discrete_Range, Analyze_Logical_Op,
	Analyze_Short_Circuit): Add calls to Check_Xtra_Parentheses.
	* par-ch5.adb (P_Condition): Move logic to Check_Xtra_Parentheses.
	* style.ads, styleg.adb, styleg.ads (Check_Xtra_Parens): Move logic
	related to expressions requiring parentheses here.