runtest: extract the logic that update timeout for slow tests
We want to use the "slow" test logic not only for "#require" clauses but also in
"#if" clauses. For this to be useful we need the logic to bump the timeout in at
least two spots. The first step it to factor it out.
#require docutils gettext
Error: the current ro localization has some rst defects exposed by
moving pager to core. These two warnings about references are expected
until the localization is corrected.
$ $TESTDIR/check-gendoc ro
checking for parse errors
gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.
gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.