Add multi-host support

This refactoring includes:
- added multi-host mode support;
- added support for graceful shutdown of the service;
- added support to flush the log buffer as it fills;
- D-Bus service xyz.openbmc_project.HostLogger replaced with SIGUSR1
  signal handler;
- self diagnostic messages now registered via phosphor-logging;
- added unit tests;
- build system migrated from autotools to meson;
- source code aligned with OpenBMC conventions.

Change-Id: If6c1dfde278af685d8563450543a6587a282c7e4
Signed-off-by: Artem Senichev <a.senichev@yadro.com>
diff --git a/src/zlib_exception.hpp b/src/zlib_exception.hpp
index b147301..54a57ea 100644
--- a/src/zlib_exception.hpp
+++ b/src/zlib_exception.hpp
@@ -1,22 +1,5 @@
-/**
- * @brief zLib exception.
- *
- * This file is part of HostLogger project.
- *
- * Copyright (c) 2020 YADRO
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (C) 2020 YADRO
 
 #pragma once
 
@@ -25,8 +8,9 @@
 #include <exception>
 #include <string>
 
-/** @class ZlibException
- *  @brief zLib exception.
+/**
+ * @class ZlibException
+ * @brief zLib exception.
  */
 class ZlibException : public std::exception
 {
@@ -34,17 +18,18 @@
     /** @brief File operation types. */
     enum Operation
     {
-        Create,
-        Write,
-        Close
+        create,
+        write,
+        close
     };
 
-    /** @brief Constructor.
+    /**
+     * @brief Constructor.
      *
-     *  @param[in] op - type of operation
-     *  @param[in] code - zLib status code
-     *  @param[in] fd - zLib file descriptor
-     *  @param[in] fileName - file name
+     * @param[in] op type of operation
+     * @param[in] code zLib status code
+     * @param[in] fd zLib file descriptor
+     * @param[in] fileName file name
      */
     ZlibException(Operation op, int code, gzFile fd,
                   const std::string& fileName);
@@ -54,5 +39,5 @@
 
   private:
     /** @brief Error description buffer. */
-    std::string what_;
+    std::string errDesc;
 };