Use x86-64 cacheinfo.c and sysconf.c for x86

Use x86-64 cacheinfo.c and sysconf.c for x86

Since _dl_x86_cpu_features is always available, we can use x86-64
cacheinfo.c and sysconf.c for both i386 and x86-64.

	* sysdeps/i386/i686/Makefile
	[$(subdir) == string] (sysdep_routines): Moved to ...
	* sysdeps/i386/Makefile: Here.
	* sysdeps/i386/i686/cacheinfo.c: Moved to ...
	* sysdeps/i386/cacheinfo.c: Here.
	* sysdeps/unix/sysv/linux/i386/sysconf.c: Removed.
	* sysdeps/unix/sysv/linux/i386/i686/sysconf.c: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/sysconf.c: Moved to ...
	* sysdeps/unix/sysv/linux/x86/sysconf.c: Here.