fix --build-from-source to work when node-pre-gyp is run directly as well as via npm
fix --build-from-source to work when node-pre-gyp is run directly as well as via npm

synthetos/node-pre-gyp,hybridgroup/node-pre-gyp,fengmk2/node-pre-gyp,fengmk2/node-pre-gyp,mapbox/node-pre-gyp,etiktin/node-pre-gyp,mapbox/node-pre-gyp,mapbox/node-pre-gyp,mojodna/node-pre-gyp,synthetos/node-pre-gyp,etiktin/node-pre-gyp,fengmk2/node-pre-gyp,fengmk2/node-pre-gyp,etiktin/node-pre-gyp,mojodna/node-pre-gyp,hybridgroup/node-pre-gyp,synthetos/node-pre-gyp,mapbox/node-pre-gyp,etiktin/node-pre-gyp,synthetos/node-pre-gyp,mapbox/node-pre-gyp,mojodna/node-pre-gyp,fengmk2/node-pre-gyp,mojodna/node-pre-gyp,hybridgroup/node-pre-gyp,etiktin/node-pre-gyp,synthetos/node-pre-gyp,mojodna/node-pre-gyp,hybridgroup/node-pre-gyp