Remove unneeded initialization for gc_trigger

src/lisp/s-expr.pla

@@ -1837,11 +1837,5 @@ new_sym("CHARS")=>natv    = @natv_chars
 new_sym("ASCII")=>natv    = @natv_ascii
 //new_sym("SYMS")=>natv     = @natv_syms
 tempstr = heapalloc(256)
-
-//
-// Set GC trigger to ~8% of available memory
-//
-
-gc_trigger = heapavail >> GC_SHIFT_AVAIL
 return modkeep | modinitkeep
 done