Fix return value in case of Essential matrix failure
Fix return value in case of Essential matrix failure

danylaksono/openMVG,openMVG/openMVG,Vinzza/openMVG,yoshidaken/openMVG,openMVG/openMVG,Vinzza/openMVG,poparteu/openMVG,openMVG/openMVG,danylaksono/openMVG,Vinzza/openMVG,mojovski/openMVG,openMVG/openMVG,caymard/openMVG,danylaksono/openMVG,Smozeley/openMVG,yoshidaken/openMVG,mojovski/openMVG,openMVG/openMVG,caymard/openMVG,poparteu/openMVG,poparteu/openMVG,Smozeley/openMVG,Smozeley/openMVG,poparteu/openMVG,mojovski/openMVG,yoshidaken/openMVG,caymard/openMVG