dffunmap - unmap clock enable and synchronous reset from FFs

    dffunmap [options] [selection]

This pass transforms FF types with clock enable and/or synchronous reset into
their base type (with neither clock enable nor sync reset) by emulating the clock
enable and synchronous reset with multiplexers on the cell input.

    -ce-only
        unmap only clock enables, leave synchronous resets alone.

    -srst-only
        unmap only synchronous resets, leave clock enables alone.