Fix clang-tidy performance warnings in system/security.

* Use const reference type for parameters, local variables,
  and for-loop index variables to avoid unnecessary copy.

Bug: 30407689
Bug: 30413223
Bug: 30413862
Change-Id: I3b9383f34e466ca6b5290bad802d535443fd0187
Test: build with WITH_TIDY=1
diff --git a/keystore/key_store_service.cpp b/keystore/key_store_service.cpp
index 759ef06..e3df13a 100644
--- a/keystore/key_store_service.cpp
+++ b/keystore/key_store_service.cpp
@@ -41,7 +41,7 @@
 
 void KeyStoreService::binderDied(const wp<IBinder>& who) {
     auto operations = mOperationMap.getOperationsForToken(who.unsafe_get());
-    for (auto token : operations) {
+    for (const auto& token : operations) {
         abort(token);
     }
 }
@@ -297,7 +297,7 @@
             ALOGI("invalid number of arguments: %zu", args->size());
             return ::SYSTEM_ERROR;
         } else if (args->size() == 1) {
-            sp<KeystoreArg> expArg = args->itemAt(0);
+            const sp<KeystoreArg>& expArg = args->itemAt(0);
             if (expArg != NULL) {
                 Unique_BIGNUM pubExpBn(BN_bin2bn(
                     reinterpret_cast<const unsigned char*>(expArg->data()), expArg->size(), NULL));
@@ -1351,7 +1351,7 @@
  *         KM_ERROR_INVALID_OPERATION_HANDLE if token is not a valid
  *         operation token.
  */
-int32_t KeyStoreService::addOperationAuthTokenIfNeeded(sp<IBinder> token,
+int32_t KeyStoreService::addOperationAuthTokenIfNeeded(const sp<IBinder>& token,
                                                        std::vector<keymaster_key_param_t>* params) {
     const hw_auth_token_t* authToken = NULL;
     mOperationMap.getOperationAuthToken(token, &authToken);