PKG_AYT, Check that package-handling facilities are installed

rst $08, defw $0000


IN:	-
OUT:	Fc=0, package-handling is installed
	Fc=1, package-handling is not available

Registers changed after return:
  A.BCDEHL/IXIY same
  .F....../.... different


Notes:
	This call must be made with success before attempting any other
	package calls

