[Ada] Fix handling of access-to-variable objects in Global and Depends
gcc/ada/
* sem_prag.ads (Collect_Subprogram_Inputs_Outputs): Update
comment; this routine is no longer used by GNATprove.
* sem_prag.adb (Find_Role): The IN parameter is on output only
when it belongs to non-function; also, the otherwise constant
object can only be written by a non-function.
(Collect_Global_Item): The IN parameter can only be written when
it belongs to non-function; also, unnest this check to make it
easier to read.