Use <string.h> & <3ds/exheader.h>, fix some bugs, etc.

also fix all warnings and use -Werror

k11_extension/source/svc/GetThreadInfo.c

@@ -23,9 +23,9 @@
 *         or requiring that modified versions of such material be marked in
 *         reasonable ways as different from the original version.
 */
+#include <string.h>
 
 #include "svc/GetThreadInfo.h"
-#include "memory.h"
 
 Result GetThreadInfoHook(s64 *out, Handle threadHandle, u32 type)
 {