lua: don't be fancy when creating shared library

(Possibly) fixes #5354

The lua shared library patch was creating the shared library with
-nostdlib -lgcc for some unknown reason, which most likely is
the reason for the link issue reported in #5354.

Fix it by dropping these arguments, so gcc gets to figure out itself
what dependencies are needed.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>