* procfs.c (to_attach): Create a procinfo for the current lwp.
Add it to gdb's thread list.
(procfs_fetch_registers, procfs_store_registers): Assume there's
always an lwp.
(procfs_wait): Don't add the main thread here.
(procfs_init_inferior): Create a procinfo for the main lwp here.
Change main thread's ptid with thread_change_ptid.
(procfs_notice_thread): Check for exited threads.
(procfs_corefile_thread_callback): Remove check for the main
process.
(procfs_make_note_section): Assume there is always a thread.
* sol-thread.c (sol_thread_attach): Clear sol_thread_active before
attaching. Change the main thread ptid with thread_change_ptid.
(sol_thread_detach): Clear sol_thread_active.
(sol_thread_wait): Check for exited threads.
(sol_thread_create_inferior): Clear sol_thread_active before
creating a new inferior. Change the main thread ptid with
thread_change_ptid.
(sol_thread_mourn_inferior): Clear sol_thread_active.
(sol_find_new_threads_callback): Check for exited threads.