a-tasatt.adb: Use 'Access instead of 'Unchecked_Access when applicable.

a-tasatt.adb: Use 'Access instead of 'Unchecked_Access when applicable.

    gcc/ada/
	* a-tasatt.adb: Use 'Access instead of 'Unchecked_Access when
	applicable. Local lifetime is the one of the package.
	(Set_Value): W is allocated on the heap.

	* g-socket.adb: Use 'Access instead of 'Unchecked_Access when
	applicable.
	(Get_Socket_Option): Optlen formal of C_Getsockopt is of an anonymous
	access type.
	(Receive_Socket): Fromlen formal of C_Recvfrom is of an anonymous
	access type.

	* s-taasde.adb: Use 'Access instead of 'Unchecked_Access when
	applicable.
	(elaboration code): Timer_Queue lifetime is the one of the
	package.

From-SVN: r129963