Fixes X509 sample app and SSL test suite

Fixes the X.509 cert_app and the SSL test suite for the non-default
configs which don't build with if MBEDTLS_PLATFORM_C isn't defined.

programs/x509/cert_app.c

@@ -29,6 +29,9 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_time       time
+#define mbedtls_time_t     time_t
 #define mbedtls_fprintf    fprintf
 #define mbedtls_printf     printf
 #endif

tests/suites/helpers.function

@@ -6,11 +6,14 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdio.h>
+#include <stdlib.h>
 #define mbedtls_printf     printf
 #define mbedtls_fprintf    fprintf
 #define mbedtls_calloc    calloc
 #define mbedtls_free       free
 #define mbedtls_exit       exit
+#define mbedtls_time       time
+#define mbedtls_time_t     time_t
 #define mbedtls_fprintf    fprintf
 #define mbedtls_printf     printf
 #define mbedtls_snprintf   snprintf
@@ -29,8 +32,6 @@ typedef UINT32 uint32_t;
 #include <stdint.h>
 #endif
 
-#include <stdio.h>
-#include <stdlib.h>
 #include <string.h>