Fix ret code in crl_app.c
diff --git a/programs/x509/crl_app.c b/programs/x509/crl_app.c
index 210d19e..687752f 100644
--- a/programs/x509/crl_app.c
+++ b/programs/x509/crl_app.c
@@ -29,8 +29,11 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdio.h>
-#define mbedtls_printf     printf
-#endif
+#include <stdlib.h>
+#define mbedtls_printf          printf
+#define MBEDTLS_EXTI_SUCCESS    EXIT_SUCCESS
+#define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
+#endif /* MBEDTLS_PLATFORM_C */
 
 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) ||  \
     !defined(MBEDTLS_X509_CRL_PARSE_C) || !defined(MBEDTLS_FS_IO)
@@ -67,7 +70,8 @@
 
 int main( int argc, char *argv[] )
 {
-    int ret = 0;
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
     unsigned char buf[100000];
     mbedtls_x509_crl crl;
     int i;
@@ -131,6 +135,8 @@
 
     mbedtls_printf( "%s\n", buf );
 
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
 exit:
     mbedtls_x509_crl_free( &crl );
 
@@ -139,7 +145,7 @@
     fflush( stdout ); getchar();
 #endif
 
-    return( ret );
+    return( exit_code );
 }
 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_X509_CRL_PARSE_C &&
           MBEDTLS_FS_IO */