Introduce a B_NO_LOCK_VECTOR flag to be used with install_io_interrupt_handler().

When specified it desigantes that the interrupt handler should not lock the
vector with a spinlock when executing the installed interrupt handlers. This
is necessary to allow the same interrupt vector to be handled in parallel on
different CPUs. And it is required for the CPU halt to work synchronously when
there is more than one AP CPU. Though the acquire_spinlock() should cause IPIs
to be processed, only this fixed the SMP_MSG_FLAG_SYNC problem for me.
Not locking is safe as long as it is guaranteed that no interrupt handler is
registered or removed while the interrupt handler is running. We can guarantee
this for the SMP interrupt handlers we install in arch_smp_init() as they are
never uninstalled. Probably this flag should be made private though.
Restored the SMP_MSG_FLAG_SYNC when entering the kernel debugger.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@23838 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/drivers/KernelExport.h

@@ -47,6 +47,7 @@ typedef int32 (*interrupt_handler)(void *data);
 
 /* Flags that can be passed to install_io_interrupt_handler() */
 #define B_NO_ENABLE_COUNTER		1
+#define B_NO_LOCK_VECTOR		2
 
 extern status_t		install_io_interrupt_handler(long interrupt_number,
 						interrupt_handler handler, void *data, ulong flags);