Fix loop initialization in table.foreach().

Reported by Daniel Steinberg.

src/lj_record.c

@@ -2233,6 +2233,7 @@ void lj_record_ins(jit_State *J)
   case BCMpri: setpriV(rcv, ~rc); ix.key = rc = TREF_PRI(IRT_NIL+rc); break;
   case BCMnum: { cTValue *tv = proto_knumtv(J->pt, rc);
     copyTV(J->L, rcv, tv); ix.key = rc = tvisint(tv) ? lj_ir_kint(J, intV(tv)) :
+    tv->u32.hi == LJ_KEYINDEX ? (lj_ir_kint(J, 0) | TREF_KEYINDEX) :
     lj_ir_knumint(J, numV(tv)); } break;
   case BCMstr: { GCstr *s = gco2str(proto_kgc(J->pt, ~(ptrdiff_t)rc));
     setstrV(J->L, rcv, s); ix.key = rc = lj_ir_kstr(J, s); } break;