LogFile uses FileOutputStream instead of custom platform implementations (#4431) (#4484)

Foundation/include/Poco/FileStream_WIN32.h

@@ -51,6 +51,9 @@ public:
 	std::streampos seekpos(std::streampos pos, std::ios::openmode mode = std::ios::in | std::ios::out);
 		/// change to specified position, according to mode
 
+	void flushToDisk();
+		/// Forces buffered data to be written to the disk
+
 	NativeHandle nativeHandle() const;
 		/// Returns native file descriptor handle