QFileInfo and QDir: use new \compares command

... to describe the comparison operators provided by these classes.

Task-number: QTBUG-120303
Change-Id: I611a1801eb038586bfe57be9b502b6f17f3d5742
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

src/corelib/io/qdir.cpp

@@ -376,6 +376,7 @@ inline void QDirPrivate::clearCache(MetaDataClearing mode)
     \ingroup shared
     \reentrant
 
+    \compares equality
 
     A QDir is used to manipulate path names, access information
     regarding paths and files, and manipulate the underlying file

src/corelib/io/qfileinfo.cpp

@@ -198,6 +198,8 @@ QDateTime &QFileInfoPrivate::getFileTime(QAbstractFileEngine::FileTime request)
     \ingroup io
     \ingroup shared
 
+    \compares equality
+
     QFileInfo provides information about a file system entry, such as its
     name, path, access rights and whether it is a regular file, directory or
     symbolic link. The entry's size and last modified/read times are also