unknown_bifuncs: call an unknown bifunc in emergency mode

[Luke-Jr]

https://sourceforge.net/tracker/?func=detail&aid=920399&group_id=3692&atid=303692

Try calling an unknown builtin from Emergency-mode:

 MOO (#2): ;mehh()
 ** 1 warnings during parsing:
 Line 2: Unknown built-in function: mehh
 #2 <- #0:bf_call_function, line 25: Invalid argument
 #2 <- ... called from #-1:emergency_mode, line 1
 #2 <- (End of traceback)
 Mar 7 11:59:23: *** PRINT_TO_STREAM: Unknown Var type =
 134646064
 => >>Unknown value<<

 This causes unexpected behaviour and server-panics
 (sometimes).
 I wasn't able to find the bug, so if you can, please gimme
 an update!

 Goblin