[Ada] Warn about obsolete uses of renamed Ada 83 packages

Ada 83 packages like Unchecked_Conversion or Text_IO are obsolete since
Ada 95. GNAT now warns about their uses when warnings on obsolescent
featured (Annex J) is active.


	* doc/gnat_ugn/building_executable_programs_with_gnat.rst
	(Warning Message Control): Update description of switch -gnatwj.
	* gnat_ugn.texi: Regenerate.
	* sem_ch10.adb (Analyze_With_Clause): Warn on WITH clauses for
	obsolete renamed units; in Ada 83 mode do not consider
	predefined renamings to be obsolete.


	* gnat.dg/renaming1.adb: Update WITH clause.
	* gnat.dg/renaming1.ads: Likewise.
	* gnat.dg/warn29.adb: Likewise.
6 files changed