logging/backend: Add missing standard includes

A few inclusions were being satisfied indirectly. To prevent breakages
in the future, include these directly.

src/common/logging/backend.cpp

@@ -3,19 +3,20 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
-#include <array>
+#include <atomic>
 #include <chrono>
 #include <climits>
 #include <condition_variable>
 #include <memory>
+#include <mutex>
 #include <thread>
+#include <vector>
 #ifdef _WIN32
 #include <share.h> // For _SH_DENYWR
 #else
 #define _SH_DENYWR 0
 #endif
 #include "common/assert.h"
-#include "common/common_funcs.h" // snprintf compatibility define
 #include "common/logging/backend.h"
 #include "common/logging/log.h"
 #include "common/logging/text_formatter.h"

src/common/logging/backend.h

@@ -4,11 +4,9 @@
 #pragma once
 
 #include <chrono>
-#include <cstdarg>
 #include <memory>
 #include <string>
 #include <string_view>
-#include <utility>
 #include "common/file_util.h"
 #include "common/logging/filter.h"
 #include "common/logging/log.h"