Ada: Fix profile conformance glitch with limited_with and incomplete type

Ada: Fix profile conformance glitch with limited_with and incomplete type

That's an old issue, but the fix is quite straightforward.

gcc/ada/
	PR ada/89159
	* sem_ch6.adb (Conforming_Types.Is_Matching_Limited_View): Return
	true when the type is an incomplete view of the non-limited view.

gcc/testsuite/
	* gnat.dg/limited_with8.adb: New test.
	* gnat.dg/limited_with8_pkg1.ads: New helper.
	* gnat.dg/limited_with8_pkg2.ads: Likewise.
	* gnat.dg/limited_with8_pkg2.adb: Likewise.