* breakpoint.h (struct breakpoint) <watchpoint_thread>: New field.
* breakpoint.c (watchpoint_in_thread_scope): New.
(update_watchpoint): Skip if the local watchpoint's thread doesn't
match the current thread, or if the current thread is running.
(watchpoint_check): Ditto.
(watch_command_1): Set the watchpoint's watchpoint_thread field.
gdb/testsuite/
* gdb.threads/local-watch-wrong-thread.c,
gdb.threads/local-watch-wrong-thread.exp: New files.
