+--- Set the last modification time of given file path in Unix epoch format.
+-- @param path String containing the path of the file or directory to read
+-- @param mtime Last modification timestamp
+-- @param atime Last accessed timestamp
+-- @return 0 in case of success nil on error
+-- @return String containing the error description (if any)
+-- @return Number containing the os specific errno (if any)
+utime = posix.utime
+