[Ada] Use membership tests in front-end

[Ada] Use membership tests in front-end

gcc/ada/

	* aspects.adb, atree.adb, atree.ads, checks.adb, contracts.adb,
	einfo.adb, errout.adb, exp_aggr.adb, exp_attr.adb, exp_cg.adb,
	exp_ch11.adb, exp_ch2.adb, exp_ch3.adb, exp_ch4.adb,
	exp_ch5.adb, exp_ch6.adb, exp_ch7.adb, exp_ch8.adb, exp_ch9.adb,
	exp_dbug.adb, exp_disp.adb, exp_intr.adb, exp_pakd.adb,
	exp_prag.adb, exp_put_image.adb, exp_smem.adb, exp_tss.adb,
	exp_unst.adb, exp_util.adb, freeze.adb, ghost.adb, gnat1drv.adb,
	inline.adb, lib-writ.adb, lib-xref-spark_specific.adb,
	lib-xref.adb, namet.adb, namet.ads, nlists.adb, par-ch10.adb,
	par-ch2.adb, par-ch3.adb, par-ch4.adb, par-ch5.adb, par-ch6.adb,
	par-prag.adb, par-util.adb, par_sco.adb, pprint.adb,
	repinfo.adb, restrict.adb, rtsfind.adb, scil_ll.adb, sem.adb,
	sem_aggr.adb, sem_attr.adb, sem_aux.adb, sem_cat.adb,
	sem_ch10.adb, sem_ch11.adb, sem_ch12.adb, sem_ch13.adb,
	sem_ch3.adb, sem_ch4.adb, sem_ch5.adb, sem_ch6.adb, sem_ch7.adb,
	sem_ch8.adb, sem_ch9.adb, sem_dim.adb, sem_disp.adb,
	sem_dist.adb, sem_elab.adb, sem_elim.adb, sem_eval.adb,
	sem_intr.adb, sem_mech.adb, sem_prag.adb, sem_res.adb,
	sem_scil.adb, sem_type.adb, sem_util.adb, sem_warn.adb,
	sinfo.adb, sinfo.ads, sprint.adb, styleg.adb, tbuild.adb,
	treepr.adb (Nkind_In, Nam_In, Ekind_In): Removed, replaced by
	membership tests.