Update key control block verification

This is a merge of http://go/wvgerrit/13752

Replace the mock's macro with a memcmp because that is
even cleaner.

Change-Id: Ie402689ca9e14a67736db7eea928204f067427ac

libwvdrmengine/oemcrypto/mock/src/oemcrypto_key_mock.h

@@ -44,14 +44,14 @@ class KeyControlBlock {
   uint32_t duration() const { return duration_; }
   void set_duration(uint32_t duration) { duration_ = duration; }
   uint32_t nonce() const { return nonce_; }
-  uint32_t verification() const { return verification_; }
+  const char* verification() const { return verification_; }
   uint32_t control_bits() const { return control_bits_; }
 
  private:
   uint32_t ExtractField(const std::vector<uint8_t>& str, int idx);
 
   bool valid_;
-  uint32_t verification_;
+  char verification_[4];
   uint32_t duration_;
   uint32_t nonce_;
   uint32_t control_bits_;