NPAPI headers bundle for building plugins

 npapi-sdk goal is to provide a set of reference NPAPI headers which all
 browser and plugin projects can use. Additionally it will contain
 utility code and sample code to make life easier for NPAPI developers.
 .
 npapi-sdk is the bundle of NPAPI headers lately decoupled from Mozilla
 sources. Gentoo Mozilla team provides a build system and packaging
 releases of it.