GNATprove analyzer for SPARK code depends on the frontend to accurately
propagate the known value of Size attribute. This was not done for
formal type parameters in generic instantiations. Now fixed.

There is no impact on compilation.

2019-08-21  Yannick Moy  <moy@adacore.com>

gcc/ada/

	* sem_ch3.adb (Analyze_Subtype_Declaration): Inherit RM_Size
	field for formal type parameters in generic instantiations.

From-SVN: r274788