IBM long double mechanical changes to support little-endian

IBM long double mechanical changes to support little-endian
http://sourceware.org/ml/libc-alpha/2013-07/msg00001.html

This patch starts the process of supporting powerpc64 little-endian
long double in glibc.  IBM long double is an array of two ieee
doubles, so making union ibm_extended_long_double reflect this fact is
the correct way to access fields of the doubles.

	* sysdeps/ieee754/ldbl-128ibm/ieee754.h
	(union ibm_extended_long_double): Define as an array of ieee754_double.
	(IBM_EXTENDED_LONG_DOUBLE_BIAS): Delete.
	* sysdeps/ieee754/ldbl-128ibm/printf_fphex.c: Update all references
	to ibm_extended_long_double and IBM_EXTENDED_LONG_DOUBLE_BIAS.
	* sysdeps/ieee754/ldbl-128ibm/e_exp10l.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/e_expl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/math_ldbl.h: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/strtold_l.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c: Likewise.