Remove references to external libs from extconf.rb
Remove references to external libs from extconf.rb

johnmarinelli/nmatrix,wlevine/nmatrix,janusnic/nmatrix,wlevine/nmatrix,agisga/nmatrix,johnmarinelli/nmatrix,johnmarinelli/nmatrix,janusnic/nmatrix,wlevine/nmatrix,janusnic/nmatrix,janusnic/nmatrix,agisga/nmatrix,agisga/nmatrix,agisga/nmatrix,johnmarinelli/nmatrix,wlevine/nmatrix