Unembed the font if this is a simple operation.
Latin based fonts can often be unembedded as a simple and fast
operation. However Unicode and symbolic fonts are more complex to
unembed and cannot be simply removed from the document. To unembed
a composite font you need to use the ReduceSizeOperation
This function returns the number of bytes of font data that were
removed as a result of this call. Note that it is possible for
multiple font objects to reference the same embedded font. In this
case each call to unembed will return the same number and the
actual font will only actually be removed from the document if all
references to it are released.