remote-file-resolve: pass back nil asap in file walk if fails.
remote-file-resolve: pass back nil asap in file walk if fails.

During a remote file resolve, if the file is not found, pass back
nil to the resolvedResults channel instead of skipping. This bug
was causing deeply nested and unsynced directories to not be
registered as pull/push worthy.

odeke-em/drive,gdm85/drive,odeke-em/drive,sselph/drive,gdm85/drive,sselph/drive,Dedsec01/drive,cacack/drive,Dedsec01/drive,gccpacman/drive,gccpacman/drive,cacack/drive