Updates to OEMCrytpo Mock

Squash merge from the widevine repo of several changes to oemcrypto
unit tests and the mock reference code.

http://go/wvgerrit/16264 Use unsigned int for count in usage table (more mock)
http://go/wvgerrit/16262 Use unsigned int for count in usage table (mock version)
http://go/wvgerrit/16247 Fix mock OEMCrypto_DeleteUsageTable
http://go/wvgerrit/16070 Fix OEMCrypto_GenerateRSASignature return values
http://go/wvgerrit/15991 Fix buffer overflow for 32-bit systems
http://go/wvgerrit/15993 Return Correct Value from OEMCrypto_RefreshKeys
http://go/wvgerrit/15880 Cast RSA_size() to int
http://go/wvgerrit/15831 Be strict about warnings for CE CDM

b/23729420
b/25221168

Change-Id: I97b91dfc672db8c586ae317977871b7d6afac4bb

libwvdrmengine/oemcrypto/mock/src/oemcrypto_usage_table_mock.cpp

@@ -241,7 +241,7 @@ UsageTable::UsageTable(CryptoEngine *ce) {
 
   // At this point, the stored table looks valid. We can load in all the
   // entries.
-  for (size_t i = 0; i < stored_table->count; i++) {
+  for (uint64_t i = 0; i < stored_table->count; i++) {
     UsageTableEntry *entry =
         new UsageTableEntry(&stored_table->entries[i].entry);
     table_[entry->pst_hash()] = entry;