psa: Fix builds without MBEDTLS_PLATFORM_C

When `MBEDTLS_PLATFORM_C` is not enabled, our PSA Crypto implementation
depends on the standard C library for functions like snprintf() and
exit(). However, our implementation was not including the proper header
files nor redefining all `mbedtls_*` symbols properly to ensure
successful builds without MBEDTLS_PLATFORM_C. Add the necessary header
files and macro definitions to our PSA Crypto implementation.

library/psa_crypto_storage.c

@@ -38,6 +38,7 @@
 #if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
 #else
+#include <stdlib.h>
 #define mbedtls_calloc   calloc
 #define mbedtls_free     free
 #endif

library/psa_crypto_storage_file.c

@@ -36,6 +36,7 @@
 #if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
 #else
+#include <stdio.h>
 #define mbedtls_snprintf snprintf
 #endif
 

programs/psa/crypto_examples.c

@@ -5,7 +5,10 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdio.h>
+#include <stdlib.h>
+#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
 #define mbedtls_printf printf
+#define mbedtls_exit exit
 #endif
 
 #define ASSERT( predicate )                                                   \

programs/psa/key_ladder_demo.c

@@ -66,6 +66,7 @@
 #define mbedtls_calloc       calloc
 #define mbedtls_free         free
 #define mbedtls_printf       printf
+#define mbedtls_exit         exit
 #endif
 #include <stdio.h>
 #include <string.h>