Don't declare calloc() and realloc() if not necessary.

acconfig.h

@@ -31,6 +31,14 @@
 
 /* The location of the semantic parser (bison.hairy).  */
 #undef XPFILE1
+
+/* Define as 1 if realloc must be declared even if <stdlib.h> is
+   included.  */
+#undef NEED_DECLARATION_REALLOC
+
+/* Define as 1 if calloc must be declared even if <stdlib.h> is
+   included.  */
+#undef NEED_DECLARATION_CALLOC
 @BOTTOM@
 
 #if defined(PROTOTYPES) || defined(__cplusplus)