Mark ____wcsto*_l_internal functions with attribute_hidden [BZ #18822]

Mark ____wcsto*_l_internal functions with attribute_hidden [BZ #18822]

Mark ____wcsto*_l_internal functions with attribute_hidden to allow
direct access to them within libc.so and libc.a without using GOT nor
PLT.

	[BZ #18822]
	* include/wchar.h (____wcstof_l_internal): New prototype.
	(____wcstod_l_internal): Likewise.
	(____wcstold_l_internal): Likewise.
	(____wcstol_l_internal): Likewise.
	(____wcstoul_l_internal): Likewise.
	(____wcstoll_l_internal): Likewise.
	(____wcstoull_l_internal): Likewise.
	(____wcstof128_l_internal): Likewise.
	* sysdeps/ieee754/float128/wcstof128.c
	(____wcstof128_l_internal): Removed.
	* sysdeps/ieee754/float128/wcstof128_l.c
	(____wcstof128_l_internal): Likewise.
	* wcsmbs/wcstod.c (____wcstod_l_internal): Likewise.
	* wcsmbs/wcstod_l.c (____wcstod_l_internal): Likewise.
	* wcsmbs/wcstof.c (____wcstof_l_internal): Likewise.
	* wcsmbs/wcstof_l.c (____wcstof_l_internal): Likewise.
	* wcsmbs/wcstol_l.c (____wcstol_l_internal): Likewise.
	* wcsmbs/wcstold.c (____wcstold_l_internal): Likewise.
	* wcsmbs/wcstold_l.c (____wcstold_l_internal): Likewise.
	* wcsmbs/wcstoll_l.c (____wcstoll_l_internal): Likewise.
	* wcsmbs/wcstoul_l.c (____wcstoul_l_internal): Likewise.
	* wcsmbs/wcstoull_l.c (____wcstoull_l_internal): Likewise.