FFI: Fix dangling CType references (again).

Reported by Sergey Kaplun. Collateral of #1360

src/lj_crecord.c

@@ -1125,6 +1125,7 @@ static int crec_call(jit_State *J, RecordFFData *rd, GCcdata *cd)
   if (ctype_isfunc(info)) {
     TRef func = emitir(IRT(IR_FLOAD, tp), J->base[0], IRFL_CDATA_PTR);
     CType *ctr = ctype_rawchild(cts, ct);
+    CTInfo ctr_info = ctr->info;  /* crec_call_args may invalidate ctr. */
     IRType t = crec_ct2irt(cts, ctr);
     TRef tr;
     TValue tv;
@@ -1133,11 +1134,11 @@ static int crec_call(jit_State *J, RecordFFData *rd, GCcdata *cd)
 		cdata_getptr(cdataptr(cd), (LJ_64 && tp == IRT_P64) ? 8 : 4));
     if (tvistrue(lj_tab_get(J->L, cts->miscmap, &tv)))
       lj_trace_err(J, LJ_TRERR_BLACKL);
-    if (ctype_isvoid(ctr->info)) {
+    if (ctype_isvoid(ctr_info)) {
       t = IRT_NIL;
       rd->nres = 0;
-    } else if (!(ctype_isnum(ctr->info) || ctype_isptr(ctr->info) ||
-		 ctype_isenum(ctr->info)) || t == IRT_CDATA) {
+    } else if (!(ctype_isnum(ctr_info) || ctype_isptr(ctr_info) ||
+		 ctype_isenum(ctr_info)) || t == IRT_CDATA) {
       lj_trace_err(J, LJ_TRERR_NYICALL);
     }
     if ((info & CTF_VARARG)
@@ -1148,7 +1149,7 @@ static int crec_call(jit_State *J, RecordFFData *rd, GCcdata *cd)
       func = emitir(IRT(IR_CARG, IRT_NIL), func,
 		    lj_ir_kint(J, ctype_typeid(cts, ct)));
     tr = emitir(IRT(IR_CALLXS, t), crec_call_args(J, rd, cts, ct), func);
-    if (ctype_isbool(ctr->info)) {
+    if (ctype_isbool(ctr_info)) {
       if (frame_islua(J->L->base-1) && bc_b(frame_pc(J->L->base-1)[-1]) == 1) {
 	/* Don't check result if ignored. */
 	tr = TREF_NIL;
@@ -1164,7 +1165,7 @@ static int crec_call(jit_State *J, RecordFFData *rd, GCcdata *cd)
 	tr = TREF_TRUE;
       }
     } else if (t == IRT_PTR || (LJ_64 && t == IRT_P32) ||
-	       t == IRT_I64 || t == IRT_U64 || ctype_isenum(ctr->info)) {
+	       t == IRT_I64 || t == IRT_U64 || ctype_isenum(ctr_info)) {
       TRef trid = lj_ir_kint(J, ctype_cid(info));
       tr = emitir(IRTG(IR_CNEWI, IRT_CDATA), trid, tr);
       if (t == IRT_I64 || t == IRT_U64) lj_needsplit(J);