[Ada] Remove System.Parameters.Single_Lock

[Ada] Remove System.Parameters.Single_Lock

2020-06-04  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* libgnarl/a-dynpri.adb, libgnarl/a-taside.adb,
	libgnarl/a-taster.adb, libgnarl/s-interr.adb,
	libgnarl/s-interr__sigaction.adb, libgnarl/s-taasde.adb,
	libgnarl/s-taenca.adb, libgnarl/s-taenca.ads,
	libgnarl/s-taprop.ads, libgnarl/s-taprop__hpux-dce.adb,
	libgnarl/s-taprop__linux.adb, libgnarl/s-taprop__mingw.adb,
	libgnarl/s-taprop__posix.adb, libgnarl/s-taprop__qnx.adb,
	libgnarl/s-taprop__solaris.adb, libgnarl/s-taprop__vxworks.adb,
	libgnarl/s-tarest.adb, libgnarl/s-tasini.adb,
	libgnarl/s-tasque.adb, libgnarl/s-tasque.ads,
	libgnarl/s-tasren.adb, libgnarl/s-tasren.ads,
	libgnarl/s-tassta.adb, libgnarl/s-tasuti.adb,
	libgnarl/s-tasuti.ads, libgnarl/s-tpoben.adb,
	libgnarl/s-tpobop.adb, libgnarl/s-tpopmo.adb,
	libgnarl/s-tposen.adb, libgnat/s-parame.ads,
	libgnat/s-parame__ae653.ads, libgnat/s-parame__hpux.ads,
	libgnat/s-parame__vxworks.ads: Remove references to Single_Lock
	and Global_Lock.