[tz] Changes in daylight saving rules in Brazil

[Paul Eggert]

The recent changes to Brazil were published as part of tzdb 2019b, 
released 2019-07-01. Evidently these changes have not propagated to your 
system, so you'll need to update it (preferably to 2019c, the current 
release). The details for this depend on your platform; as an R user, 
you might consult 
<https://svn.r-project.org/R/trunk/src/extra/tzone/Notes> to get started.