lbase64: build as generic-package instead of luarocks

lbase64: build as generic-package instead of luarocks

The author of lbase64 maintains 3 separate versions of the package for
the 3 Lua versions. Only the 5.1 version is uploaded to luarocks, so
that is the one we currently support in Buildroot.

However, the three versions are nearly identical. With a small patch,
this allows us to support all Lua versions from a single tarball.

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>