cleanup library and some basic tests. Includes, add guards to includes
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index c649129..30da95a 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -34,15 +34,16 @@
 
 #include "polarssl/ssl_cache.h"
 
+#include <string.h>
+
 #if defined(POLARSSL_PLATFORM_C)
 #include "polarssl/platform.h"
 #else
+#include <stdlib.h>
 #define polarssl_malloc     malloc
 #define polarssl_free       free
 #endif
 
-#include <stdlib.h>
-
 void ssl_cache_init( ssl_cache_context *cache )
 {
     memset( cache, 0, sizeof( ssl_cache_context ) );