[Ada] Remove AAMP from compiler sources

[Ada] Remove AAMP from compiler sources

gcc/ada/

	* ada_get_targ.adb, aspects.ads, checks.adb, cstand.adb,
	einfo.ads, exp_attr.adb, freeze.adb, get_targ.adb,
	libgnat/a-textio.ads, libgnat/g-memdum.ads,
	libgnat/s-scaval__128.adb, libgnat/s-scaval.adb, make.adb,
	osint.ads, par-prag.adb, sem_ch13.adb, sem_prag.adb,
	sem_prag.ads, set_targ.adb, set_targ.ads, snames.ads-tmpl,
	targparm.ads, types.ads: Remove AAMP-specific code.
	* switch.ads: Minor reformatting.
	* gen_il-fields.ads, gen_il-gen.adb,
	gen_il-gen-gen_entities.adb, gen_il-types.ads, einfo-utils.adb,
	einfo-utils.ads: Package Types now contains "type Float_Rep_Kind
	is (IEEE_Binary);", which used to also have an enumeral AAMP.
	Gen_IL can't handle fields of this type, which would be zero
	sized. Therefore, we move the Float_Rep field into Einfo.Utils
	as a synthesized attribute. (We do not delete the field
	altogether, in case we want new floating-point representations
	in the future.)
	* doc/gnat_rm/implementation_defined_pragmas.rst,
	doc/gnat_rm/implementation_defined_aspects.rst,
	doc/gnat_ugn/building_executable_programs_with_gnat.rst,
	doc/gnat_ugn/the_gnat_compilation_model.rst: Remove
	AAMP-specific documentation.
	* gnat_rm.texi, gnat_ugn.texi: Regenerate.