* {i386-tdep.c, m68k-tdep.c, mips-tdep.c, sparc-tdep.c}

	* {i386-tdep.c, m68k-tdep.c, mips-tdep.c, sparc-tdep.c}
	  (supply_gregset, fill_gregset, supply_fpregset, fill_fpregset):
	Use "regi" for local indexing through register numbers, reserving
	"regno" for the name of a specific register passed as an input
	parameter.  Fix bug propagated through all versions that sometimes
	used regno as an index when it should have been regi, thus using
	-1 as an index in some cases.