Ömer Sinan Ağacan authored Oct 16, 2019 and Marge Bot committed Oct 29, 2019

Make it evident in the constructors that the final interface is only
available when HscStatus is not HscRecomp.

(When HscStatus == HscRecomp we need to finish the compilation to get
the final interface)

`Maybe ModIface` return value of hscIncrementalCompile and the partial
`expectIface` function are removed.