The -gnatX switch enables naming a prefixed view of a subprogram with an
untagged prefix. Compiling such a reference where the prefix is of a modular
type could result in an internal compiler error.

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

gcc/ada/

	* sem_ch4.adb
	(Analyze_Selected_Component): Avoid initializing the local
	variable Comp if the variable is not going to be subsequently
	referenced. This is a correctness issue because the call to
	First_Entity can fail.