ada: Move warnings switches

ada: Move warnings switches

This patch moves warning switches from Opt into Warnsw, fixes some minor
discrepancies, and cleans up the code.

No change in behavior.

gcc/ada/

	* warnsw.ads, warnsw.adb: Move warning flags here from package
	Opt. Rename Warning_Record to be Warnings_State. Use an array
	instead of a record; this simplifies the code. Add renamings of
	all the array components for easy reference outside this package.
	Pass the "Family" to Set_Warning_Switch. Use more table-driven
	code. Misc cleanup and comment fixes.
	* opt.ads: Move warning switches to Warnsw.
	* gnat1drv.adb
	(Adjust_Global_Switches): Expanded names needed.
	* inline.ads: Rename Warning_Record to be Warnings_State.
	* sem_ch12.adb: Likewise.
	* sem_prag.adb: Use new Set_Warning_Switch.
	* contracts.adb, errout.adb, exp_aggr.adb, exp_ch11.adb: Adjust
	imports for move to Warnsw.
	* exp_ch5.adb, exp_prag.adb, exp_util.adb, frontend.adb: Likewise.
	* layout.adb, lib-xref.adb, restrict.adb, scn.adb, sem_aggr.adb:
	Likewise.
	* sem_attr.adb, sem_case.adb, sem_ch10.adb, sem_ch11.adb:
	Likewise.
	* sem_ch13.adb, sem_ch3.adb, sem_ch4.adb, sem_ch5.adb: Likewise.
	* sem_ch6.adb, sem_ch7.adb, sem_ch8.adb, sem_elab.adb: Likewise.
	* sem_eval.adb, sem_res.adb, sem_util.adb, sem_warn.adb: Likewise.
	* switch-c.adb: Likewise.