GLupeN64 is mupen64plus + RSP-HLE + GLideN64 + libretro.

How is this different from mupen64plus-libretro?

mupen64plus-libretro tries to emulate the complete mupen64plus experience
(think multiple graphic and RSP plugins). They also make modifications to
the code as they see fit.

Because mupen64plus is built to be modular it is difficult to "convert"
that project to a libretro core, since you end up with functions with the
same name (for instance multiple functions named "PluginStartup").

Many modifications had to be made to the mupen64plus-libretro code to get
it to work inside libretro. As a result, it differs quite greatly from vanilla
mupen64plus (there is no up to date GLideN64 implmentation for example).

By choosing one RSP implentation (rsp-hle) and one graphics plugin (GLideN64),
we will be able to keep the code in line with upstream, and maintaining the
code will be much simpler.

To build the debugging symbols use:
  DEBUG=1 ./GLupeN64.SlackBuild