[2123] Small performance improvements in tests

As suggested by cppcheck.

src/lib/log/tests/logger_name_unittest.cc

@@ -31,9 +31,9 @@ using namespace isc::log;
 
 class LoggerNameTest : public ::testing::Test {
 public:
-    LoggerNameTest() {
-        name_ = getRootLoggerName();
-    }
+    LoggerNameTest() :
+        name_(getRootLoggerName())
+    {}
     ~LoggerNameTest() {
         setRootLoggerName(name_);
     }

src/lib/server_common/tests/socket_requestor_test.cc

@@ -450,7 +450,7 @@ private:
     // NOTE: client_fd could leak on exception.  This should be cleaned up.
     // See the note about SocketSessionReceiver in socket_request.cc.
     void
-    serve(const std::vector<std::pair<std::string, int> > data) {
+    serve(const std::vector<std::pair<std::string, int> >& data) {
         const int client_fd = accept(fd_, NULL, NULL);
         if (client_fd == -1) {
             isc_throw(Unexpected, "Error in accept(): " << strerror(errno));