Make ilogb wrappers type-generic.

Make ilogb wrappers type-generic.

This patch converts the ilogb wrappers (which set errno directly
rather than doing anything with __kernel_standard) to use the
type-generic template machinery.  This is intended as preparation for
adding llogb.

Tested for x86_64 and x86, and tested compile for other architectures
with build-many-glibcs.py.

	* math/w_ilogb_template.c: New file.  Based on math/w_ilogb.c.
	* math/w_ilogb.c: Remove.
	* math/w_ilogbf.c: Likewise.
	* math/w_ilogbl.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/w_ilogb.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/w_ilogbl.c: Likewise.
	* math/Makefile (gen-libm-calls): Add w_ilogbF.
	(libm-calls): Remove w_ilogbF.
	* sysdeps/ieee754/ldbl-opt/math-type-macros-double.h
	(LDOUBLE_ilogbl_libm_version): New macro.