Fix compiler warning: unused variable 'j'
Fix compiler warning: unused variable 'j'

../src/pcsc-client.cc:109:19: warning: unused variable 'j' [-Wunused-variable]
                unsigned int i, j, k, nbReaders;
                                ^

jokesterfr/node-pcsc,jokesterfr/node-pcsc,jokesterfr/node-pcsc