Warn on unparenthesized (in)equality as operand of and/or/xor, as this
is a known source of confusion.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* sem_res.adb (Resolve_Equality_Op): Warn when -gnatwq is used
	(the default) and the problematic case is encountered.