Sanitize username used for constructing log filenames.
Sanitize username used for constructing log filenames.

On Windows, os/user.Current may return a username containing a backslash.

justintung/glog,wmark/glog,kubernetes/klog,hongrich/glog,jadekler/git-go-woodsman,strangemonad/clog,youleiy/glog,bruceauyeung/glog,michael-berlin/glog,airbrake/glog,kubernetes/klog,nckturner/glog,aolu11/glog,barakmich/glog,golang/glog,yext/glog,snowsnail/glog,zhangskills/glog,skia-dev/glog,zj8487/glog,thomasf/lg,viki-org/glog,going/glog,chinawebeye/glog,zenoss/glog,sitano/glog,chinanjjohn2012/glog,winxxp/glog,emicklei/glog