remove GCC warnings in lua.cpp [-Wshadow]

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9871 387891d4-d844-0410-90c0-e4c51a9137d3
Coverity: potential array out of bounds read in ade_set_object_with_breed

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9872 387891d4-d844-0410-90c0-e4c51a9137d3