Add support for the Linux NPTL (New POSIX Thread Library) thread

Add support for the Linux NPTL (New POSIX Thread Library) thread
implementation.
* arch.h, lwp-pool.c, lwp-pool.h, stock-breakpoints.c:
* stock-breakpoints.h: New files.
* gdbserv-thread-db.h (continue_lwp, singlestep_lwp, attach_lwp)
(stop_lwp): Move these ...
* lwp-ctrl.h: ... to here (new file).
* server.h (struct child_process): Include a pointer to the
architecture object, a breakpoint table, and a pointer to the
"focus thread".
* linux-target.c: Create architecture objects for the i386 and
FRV, and describe breakpoints for those architectures.
#include "arch.h".
[STOCK_BREAKPOINTS]: #include "stock-breakpoints.h".
(allocate_empty_arch): New function.
[X86_LINUX_TARGET] (stock_table_to_x86, x86_table_to_stock)
(stock_bp_to_x86, x86_bp_to_stock, x86_make_bp_table, x86_set_bp)
(x86_delete_bp, x86_bp_hit_p, x86_make_arch): New functions.
(MAKE_ARCH): #define to call x86_make_arch.
[X86_LINUX_TARGET] (stock_table_to_frv, frv_table_to_stock)
(stock_bp_to_frv, frv_bp_to_stock, frv_make_bp_table, frv_set_bp)
(frv_delete_bp, frv_bp_hit_p, frv_make_arch): New functions.
(MAKE_ARCH): #define to call frv_make_arch.
(linux_attach): If MAKE_ARCH is #defined, create an architecture
object for this process.  And if we have an architecture object,
make a breakpoint table.
* thread-db.c: #include <assert.h>, "arch.h", "lwp-ctrl.h", and
"lwp-pool.h".
(struct gdbserv_thread): Remove state-tracking flags 'attached',
'stopped', 'waited', and 'stepping'; all that state is handled
inside lwp-pool.c now.
(add_thread_to_list): Zero the entire newly allocated thread
structure.
(thread_list_lookup_by_lid): Prefer threads whose ti_lid values
are different from that of the main process.
(thread_db_state_str, thread_db_type_str): Don't include
formatting spaces here.
(thread_db_event_str): New function.
(thread_debug_name): New function.
(get_thread_signals): Return a value indicating success or failure.
(ignore_thread_signal): New function.
(using_thread_db_events, create_notification, death_notification)
(get_event_notification, set_event_breakpoint)
(insert_thread_db_event_breakpoints)
(delete_thread_db_event_breakpoints, request_thread_db_events)
(hit_thread_db_event_breakpoint, handle_thread_db_event): New
variables and functions, for using libthread_db's event interface.
(thread_db_open): Gather error-handling code next to the operation
that might fail.  Decide here whether to use the signal-based
debugging interface, or the event-based debugging interface.
(stop_thread, stop_all_threads, struct event_list, pending_events)
(pending_events_listsize, pending_events_top, add_pending_event)
(select_pending_event, send_pending_signals, wait_all_threads):
Deleted; we now use lwp-pool.c for all this.
(attach_thread, continue_thread, continue_all_threads)
(singlestep_thread, thread_db_singlestep_program)
(thread_db_continue_thread, thread_db_singlestep_thread): Use the
lwp-pool.c functions, instead of calling the lwp manipulation
functions directly and managing state here.  Keep track of the
focus thread.
(find_new_threads_callback): Always call attach_thread.  If we're
using libthread_db events, enable event reporting for the new
thread.
(update_thread_list): Take the current child process as an
argument; if the current focus thread disappears, clear the
process's focus_thread pointer.
(thread_db_thread_next): Pass the current child process to
update_thread_list.
(thread_db_thread_info): Reformat thread descriptions.  Mark
threads whose pid is equal to the process ID.
(thread_db_check_child_state): Use the lwp-pool functions, instead
of calling waitpid and the old stop-all-threads functions.  If we
have a focus thread, only check for a status on that thread.
Check for libthread_db events.  Use ignore_thread_signal, instead
of writing it out.
(thread_db_break_program): New function.
(thread_db_attach): Register it as the target's 'break_program'
method.  Always preload the symbol list with the names we'll need
for the signal-based interface, even if we have td_symbol_list.
Use lwp_pool_new_stopped to register the initial thread.  Clear
the focus thread.
* ptrace-target.c: #define _GNU_SOURCE and #include <sys/types.h>
and <linux/unistd.h>, to get declarations for the functions we
need.
#include "lwp-ctrl.h".
(continue_lwp, singlestep_lwp, attach_lwp): Remove
unnecessary 'extern' keywords.  Move pre-function comments to
lwp-ctrl.h.  Take an ordinary 'pid_t', not an 'lwpid_t', since
we're calling ptrace / tkill, and that's what they expect; rename
arguments accordingly.  Preserve value of errno across calls to
fprintf when reporting errors.
(kill_lwp): All the above, and use tkill system call if available.
* configure.in: Whenever we include thread-db.o in TARGET_MODULES,
also include lwp-pool.o.
On i386 and FRV Linux, use the stock-breakpoints module.
* config.in: Add template for STOCK_BREAKPOINTS.
* Makefile.am (EXTRA_rda_SOURCES): Include stock-breakpoints.c.
* Makefile.in, aclocal.m4, configure: Regenerated.