[Ada] Fix run-time segfault with derived access-to-subprogram type

[Ada] Fix run-time segfault with derived access-to-subprogram type

This fixes a segfault at run time for the call to a local subprogram
through an access value if the type of this access value is derived
from an initial access-to-subprogram type and the access value was
originally obtained with the initial type.

2019-09-19  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* sem_ch3.adb (Build_Derived_Access_Type): If this is an access-
	to-subprogram type, copy Can_Use_Internal_Rep from the parent.

gcc/testsuite/

	* gnat.dg/access9.adb: New testcase.

From-SVN: r275945