* lin-lwp.c (normal_mask, blocked_mask): New variables.

* lin-lwp.c (normal_mask, blocked_mask): New variables.
(lin_lwp_wait): Block SIGCHLD here if it isn't already blocked.
(lin_lwp_mourn_inferior): Restore the origional signal mask, and
reset the mask of blocked signals.
(_initialize_lin_lwp): Don't block SIGCHLD here, but do initialize
suspend_mask and blocked_mask.  This makes us pass
gdb.base/sigall.exp for Linux/x86 now.
(lin_thread_get_thread_signals): Treat the LinuxThreads "cancel"
signal similarly to SIGCHLD in the generic code.  Avoids GDB being
terminated by a Real-time signal.