[Ada] No Storage_Error for an oversized disabled ghost array object

[Ada] No Storage_Error for an oversized disabled ghost array object

In some cases where the size computation for an object declaration will
unconditionally overflow, the FE generates code to raise Storage_Error
at the point of the object declaration (and may generate an associated
warning). Don't do this if the object declaration is an ignored (i.e.,
disabled) ghost declaration.

2019-09-18  Steve Baird  <baird@adacore.com>

gcc/ada/

	* freeze.adb (Freeze_Object_Declaration): Do not call
	Check_Large_Modular_Array when the object declaration being
	frozen is an ignored ghost entity.

gcc/testsuite/

	* gnat.dg/ghost7.adb, gnat.dg/ghost7.ads: New testcase.

From-SVN: r275845