* linux-nat.h: New file.
* linux-nat.c: Include linux-nat.h.
* lin-lwp.c: Include linux-nat.h.
Move struct lwp_info def to linux-nat.h.
* linux-proc.c: Include linux-nat.h.
(linux_make_note_section): Iterate over lwps instead of threads.
(linux_do_thread_registers): Use lwp instead of merged pid.
* config/nm-linux.h: Move miscelaneous def'ns to linux-nat.h.
* Makefile.in (lin-lwp.o, linux-proc.o, linux-nat.o):
Add dependency on linux_nat_h.