Frees a metafile.
free-metafile releases the window system storage used by the metafile.
free-metafile must be called when the metafile is no longer needed, to avoid memory leaks.
free-metafile is supported on GTK+ only where Cairo is supported (GTK+ 2.8 and later).
free-metafile is not implemented on X11/Motif.
CAPI User Guide and Reference Manual (Macintosh version) - 3 Aug 2017