[Ada] Compiler crash with -gnatR2 and with of child

[Ada] Compiler crash with -gnatR2 and with of child

gcc/ada/

	* repinfo.adb (List_Entities): The code was assuming that if we
	encounter a package in the current scope, then it must be
	a (physically) nested package.  That was wrong, because it could
	be a child package.  Avoid recursing into child packages; they
	have not been annotated with representation information, and
	-gnatR2 queries that information.