Add sock options and explicitly set payload size for plan 9 mounts
Add sock options and explicitly set payload size for plan 9 mounts

Signed-off-by: Kathryn Baldauf <f9c2fbf13a17fb5274acf31a52eb81f1fe91283d@microsoft.com>

rn/opengcs,Microsoft/hcsshim,jterry75/opengcs,jterry75/opengcs,rn/opengcs,jterry75/opengcs