x86: Rename glibc.tune.ifunc to glibc.tune.hwcaps

Rename glibc.tune.ifunc to glibc.tune.hwcaps and move it to
sysdeps/x86/dl-tunables.list since it is x86 specicifc.  Also
change type of data_cache_size, data_cache_size and
non_temporal_threshold to unsigned long int to match size_t.
Remove usage DEFAULT_STRLEN from cpu-tunables.c.

	* elf/dl-tunables.list (glibc.tune.ifunc): Removed.
	* sysdeps/x86/dl-tunables.list (glibc.tune.hwcaps): New.
	Remove security_level on all fields.
	* manual/tunables.texi: Replace ifunc with hwcaps.
	* sysdeps/x86/cpu-features.c (TUNABLE_CALLBACK (set_ifunc)):
	Renamed to ..
	(TUNABLE_CALLBACK (set_hwcaps)): This.
	(init_cpu_features): Updated.
	* sysdeps/x86/cpu-features.h (cpu_features): Change type of
	data_cache_size, data_cache_size and non_temporal_threshold to
	unsigned long int.
	* sysdeps/x86/cpu-tunables.c (DEFAULT_STRLEN): Removed.
	(TUNABLE_CALLBACK (set_ifunc)): Renamed to ...
	(TUNABLE_CALLBACK (set_hwcaps)): This.  Update comments.  Don't
	use DEFAULT_STRLEN.