Hide internal sysinfo functions [BZ #18822]

Hide internal sysinfo functions [BZ #18822]

Hide internal sysinfo functions to allow direct access within libc.so
and libc.a without using GOT nor PLT.

	[BZ #18822]
	* include/sys/sysinfo.h (__get_nprocs_conf): Add
	libc_hidden_proto.
	(__get_nprocs): Likewise.
	(__get_phys_pages): Likewise.
	(__get_avphys_pages): Likewise.
	(__get_child_max): Add attribute_hidden.
	* misc/getsysstats.c (__get_nprocs_conf): Add libc_hidden_def.
	(__get_nprocs): Likewise.
	(__get_phys_pages): Likewise.
	(__get_avphys_pages): Likewise.
	* sysdeps/mach/getsysstats.c (__get_nprocs_conf): Add
	libc_hidden_def.
	(__get_nprocs): Likewise.
	(__get_phys_pages): Likewise.
	(__get_avphys_pages): Likewise.
	* sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs): Add
	libc_hidden_def.
	(__get_nprocs_conf): Likewise.
	(__get_phys_pages): Likewise.
	(__get_avphys_pages): Likewise.