Slightly extending commit 16b0520a9

[Alex]

Commit 16b0520a9 changed various Fcar/Fcdr calls into XCAR/XCDR, but I
believe I see two more instances where this change can also be applied.
In both cases, XCDR is already being applied on XCDR (args), so XCAR
should also be fine.

diff --git a/src/eval.c b/src/eval.c
index e5900382de..d132959f0c 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -396,7 +396,7 @@ usage: (if COND THEN ELSE...)  */)
   cond = eval_sub (XCAR (args));
 
   if (!NILP (cond))
-    return eval_sub (Fcar (XCDR (args)));
+    return eval_sub (XCAR (XCDR (args)));
   return Fprogn (XCDR (XCDR (args)));
 }
 
@@ -806,7 +806,7 @@ usage: (defconst SYMBOL INITVALUE [DOCSTRING])  */)
   if (CONSP (Fcdr (XCDR (XCDR (args)))))
     error ("Too many arguments");
 
-  tem = eval_sub (Fcar (XCDR (args)));
+  tem = eval_sub (XCAR (XCDR (args)));
   if (!NILP (Vpurify_flag))
     tem = Fpurecopy (tem);
   Fset_default (sym, tem);