cmd/upspin: typo, exitf should be Exitf causing build failure
cmd/upspin: typo, exitf should be Exitf causing build failure

Change-Id: I25442d36b35aa362c4f2818e946a71821b785875
Reviewed-on: https://upspin-review.googlesource.com/8180
Reviewed-by: Eduardo Pinheiro <c9d6fd76b920b269b838bbb70f683c6db503d8d1@gmail.com>

upspin/upspin,upspin/upspin