Fix compiler warnings

Merge from Widevine repo of http://go/wvgerrit/43420

Remove or mark unused variables.  Fix unsigned/signed comparisons.

bug: 73390805
test: unit tests
Change-Id: Ic523400a5decf82fae733042b260e0c39a087cd3

libwvdrmengine/mediadrm/test/WVDrmPlugin_test.cpp

@@ -730,7 +730,6 @@ TEST_F(WVDrmPluginTest, QueriesKeyStatus) {
     for (std::map<std::string, std::string>::iterator itr =
                 expectedLicenseStatus.begin();
         itr != expectedLicenseStatus.end(); ++itr) {
-      const std::string& key = itr->first;
       keyValuePair.value = hLicenseStatus[i++].value;
       EXPECT_EQ(itr->second.c_str(), std::string(keyValuePair.value.c_str()));
     }
@@ -1409,7 +1408,6 @@ TEST_F(WVDrmPluginTest, FailsGenericMethodsWithoutAnAlgorithmSet) {
   std::vector<uint8_t> input;
   std::vector<uint8_t> iv;
   std::vector<uint8_t> output;
-  bool match;
 
   // Provide expected behavior to support session creation
   EXPECT_CALL(*cdm, OpenSession(StrEq("com.widevine"), _, _, _, _))
@@ -1697,7 +1695,6 @@ TEST_F(WVDrmPluginTest, CallsGenericVerify) {
   message.assign(messageRaw, messageRaw + kDataSize);
   std::vector<uint8_t> signature;
   signature.assign(signatureRaw, signatureRaw + kSignatureSize);
-  bool match;
 
   {
     InSequence calls;
@@ -2364,7 +2361,6 @@ TEST_F(WVDrmPluginTest, CanSetSessionSharing) {
   }
 
   WVDrmPlugin plugin(cdm.get(), appPackageName, &crypto, false);
-  Status res;
 
   // Test turning on session sharing
   Status status = plugin.setPropertyString(hidl_string("sessionSharing"),
@@ -2461,4 +2457,3 @@ TEST_F(WVDrmPluginTest, AllowsStoringOfSessionSharingId) {
 }  // namespace drm
 }  // namespace hardware
 }  // namespace wvdrm
-