release 2019-06-01
Add GCC 9.x to the Travis CI matrix. Change-Id: I5f7e3ea5fdd23ff181f8d1037e86f7578d21ab0b Reviewed-on: https://code-review.googlesource.com/c/re2/+/41350 Reviewed-by: Paul Wankadia <junyer@google.com>