Hello,

Today I tried to `guix install pioneer` and it seems there is no substitute.  It
very quickly fails to build from source with this error in log:

-- Checking for module 'sigc++-2.0'
--   No package 'sigc++-2.0' found
CMake Error at /gnu/store/aain9m7r37jlzd21kvgvrkhc2pm7mk1w-cmake-minimal-3.21.3/share/cmake-3.21/Modules/FindPkgConfig.cmake:562 (message):
   A required package was not found