bug#25425: lua does not set search paths

[Ricardo Wurmus]

The lua interpreter packages do not set native search paths, so they
cannot find lua modules.

  $ guix environment --ad-hoc lua lua-lpeg
  $ lua
  > require('lpeg')
  … ERROR …

However:

  $ guix environment --ad-hoc lua lua-lpeg
  $ export 
LUA_PATH="$GUIX_ENVIRONMENT/share/lua/5.3/?.lua;$GUIX_ENVIRONMENT/share/lua/5.3/?/?.lua"
  $ export 
LUA_CPATH="$GUIX_ENVIRONMENT/lib/lua/5.3/?.so;$GUIX_ENVIRONMENT/lib/lua/5.3/?/?.so"
  $ lua
  > require('lpeg')
  table: 0x1b80300


--
Ricardo

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