ada: Spurious error on generalized prefix notation

ada: Spurious error on generalized prefix notation

The compiler reports a spurious error when a primitive function of
an untagged type that returns an array type is invoked using the
prefix notation, and the sources are compiled with language
extensions enabled.

gcc/ada/ChangeLog:

	* sem_util.adb (Needs_One_Actual): Add support for untagged record
	types when the sources are compiled with Core Extensions allowed.