Undo last patch.

Undo last patch.

libgcc/
2020-11-04  Michael Meissner  <meissner@linux.ibm.com>

	Undo:
	PR libgcc/97543
	* config/rs6000/t-linux (HOST_LIBGCC2_CFLAGS): Don't set
	-mlong-double-128 for all modules.  Instead set
	-mno-gnu-attributes.
	(IBM128_OBJS): New make variable for long double support.
	(IBM128_S_OBJS): New make variable for long double support.
	(IBM128_ALL_OBJS): New make variable for long double support.
	(IBM128_CFLAGS): New make variable for long double support.