MXS-2014 Add mxb::Log class for convenience

In tests, the log can now be setup as

    int main()
    {
        mxb::Log log;
        ...
    }

That will initialize the log so that it logs to a file called
<program-name>.log in the current directory and finalize it
when the program exits.

maxutils/maxbase/include/maxbase/log.hh

@@ -0,0 +1,74 @@
+#pragma once
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2022-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include <maxbase/ccdefs.hh>
+#include <stdexcept>
+#include <maxbase/log.h>
+
+/**
+ * @brief Initialize the log
+ *
+ * This function initializes the log using
+ * - the program name as the syslog ident,
+ * - the current directory as the logdir, and
+ * - the default log name (program name + ".log").
+ *
+ * @param target  The specified target for the logging.
+ *
+ * @return True if succeeded, false otherwise.
+ */
+bool mxb_log_init(mxb_log_target_t target = MXB_LOG_TARGET_FS)
+{
+    return mxb_log_init(nullptr, ".", nullptr, target, nullptr);
+}
+
+namespace maxbase
+{
+
+/**
+ * @class Log
+ *
+ * A simple utility RAII class where the constructor initializes the log and
+ * the destructor finalizes it.
+ */
+class Log
+{
+    Log(const Log&) = delete;
+    Log& operator=(const Log&) = delete;
+
+public:
+    Log(const char* ident,
+        const char* logdir,
+        const char* filename,
+        mxb_log_target_t target,
+        mxb_log_context_provider_t context_provider)
+    {
+        if (!mxb_log_init(ident, logdir, filename, target, context_provider))
+        {
+            throw std::runtime_error("Failed to initialize the log.");
+        }
+    }
+
+    Log(mxb_log_target_t target = MXB_LOG_TARGET_FS)
+        : Log(nullptr, ".", nullptr, target, nullptr)
+    {
+    }
+
+    ~Log()
+    {
+        mxb_log_finish();
+    }
+};
+
+}