[Ada] Allow inlining for proof inside generics

[Ada] Allow inlining for proof inside generics

For local subprograms without contracts inside generics, allow their
inlining for proof in GNATprove mode. This requires forbidding the
inlining of subprograms which contain references to object renamings,
which would be replaced in the SPARK expansion and violate assumptions
of the inlining code.

gcc/ada/

	* exp_spark.adb (Expand_SPARK_Potential_Renaming): Deal with no
	entity case.
	* inline.ads (Check_Object_Renaming_In_GNATprove_Mode): New
	procedure.
	* inline.adb (Check_Object_Renaming_In_GNATprove_Mode): New
	procedure.
	(Can_Be_Inlined_In_GNATprove_Mode): Remove case forbidding
	inlining for subprograms inside generics.
	* sem_ch12.adb (Copy_Generic_Node): Preserve global entities
	when inlining in GNATprove mode.
	* sem_ch6.adb (Analyse_Subprogram_Body_Helper): Remove body to
	inline if renaming is detected in GNATprove mode.