Add needed headers for including mbstate_t and exit()

Upstream-Status: Inappropriate [Reconfigure will solve it]
Signed-off-by: Khem Raj <raj.khem@gmail.com>
--- a/configure
+++ b/configure
@@ -3422,6 +3422,7 @@ rm -f "conftest.$ac_objext" "conftest.$a
   cat >"conftest.$ac_ext" <<_ACEOF
 #line 3423 "configure"
 #include "confdefs.h"
+#include <stdlib.h>
 $ac_declaration
 int
 main (void)
@@ -12997,6 +12998,7 @@ cat >"conftest.$ac_ext" <<_ACEOF
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <wchar.h>
 #ifdef HAVE_LIBUTF8_H
 #include <libutf8.h>
 #endif