Entitlement rotation support

Updates also include:
- Add APIs to query current Simulcrypt channel & stream status;
- EMM format change (used only to carry fingerprinting and service
blocking info);
- Key fetcher example to use curl key fetcher.

common/rsa_util.h

@@ -16,7 +16,7 @@
 
 #include <string>
 
-#include "openssl/rsa.h"
+#include "openssl/pem.h"
 
 namespace widevine {
 namespace rsa_util {