Fix missing include in some files

Add it in all files that use mbedtls_plaform_memset() but didn't already
include platfom_util.h.

In some configurations it just happened to work, either because it was
included indirectly or because the part of the code that used that function
was disabled, but it some configurations it broke, so let's fix it properly.

library/debug.c

@@ -42,6 +42,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
+#include "mbedtls/platform_util.h"
 
 #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
     !defined(inline) && !defined(__cplusplus)