[patch] get_scno should test TCB_INSYSCALL at the beginning

[Roland McGrath]

If there is an actual bug caused by the current code, please post a test
case to demonstrate it.  I am not convinced your patch is safe, because
get_scno sets various global variables that may be used by syscall_fixup.
(Yes, the code is horrible spaghetti and was that way before I got to it.
I'm just trying not to make it worse.)


Thanks,
Roland