Fix build error

Include `platform.h` in `aes.c` and `gcm.c` to include the
platform errors.

Author: Ron Eldor

library/aes.c

@@ -36,6 +36,7 @@
 #include <string.h>
 
 #include "mbedtls/aes.h"
+#include "mbedtls/platform.h"
 #include "mbedtls/platform_util.h"
 #if defined(MBEDTLS_PADLOCK_C)
 #include "mbedtls/padlock.h"

library/gcm.c

@@ -48,9 +48,8 @@
 
 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
 #include "mbedtls/aes.h"
-#if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
-#else
+#if !defined(MBEDTLS_PLATFORM_C)
 #include <stdio.h>
 #define mbedtls_printf printf
 #endif /* MBEDTLS_PLATFORM_C */