[Ada] Internal error compiling formal instance of generic with Initial_Condition

[Ada] Internal error compiling formal instance of generic with Initial_Condition

Prevent the compiler from failing with an internal error in some cases involving
an instance of a generic which takes as a formal parameter an instance of a
second generic, where the second generic has an Initial_Condition aspect
specification.

gcc/ada/

	* contracts.adb
	(Analyze_Package_Contract): Do not analyze the contract of a
	temporary package created just to check conformance of an actual
	package.