net: extend TestVariousDeadlines1Proc timeout
net: extend TestVariousDeadlines1Proc timeout

TestVariousDeadlines1Proc was flaky on my system,
failing on about 5% of runs.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/89830045

apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang