Adding a new library

[Techfreakworm]

Hello, 
Can anyone provide with a link to patch where an external library was added assuming that the tarball for library is already uploaded on gimli? Or a code pointer for the same? 
Another question is, if the external library requires a dependency like 'premake4', is it necessary to build it from source (tarball) too while building Libreoffice? Or the built 'premake4' can be used as it is? (premake4.4 Beta is required for the process which isn't available on online repositories to be fetched by apt-get command as dependency issue)