Merge remote-tracking branch 'tor-github/pr/392' into maint-0.2.9

## (Linux only) Use the latest Linux image (Ubuntu Trusty)

dist: trusty

## (Linux only) Download our dependencies

## Download our dependencies

addons:

  ## (Linux only)

  apt:

    packages:

      ## Required dependencies

      - libevent-dev

      ## Ubuntu comes with OpenSSL by default

      #- libssl-dev

      - zlib1g-dev

      ## Optional dependencies

      - libcap-dev

      - libscrypt-dev

      - libseccomp-dev

      ## Conditional dependencies

      ## Conditional build dependencies

      ## Always installed, so we don't need sudo

      - asciidoc

      - docbook-xsl

      - docbook-xml

      - xmlto

  ## (OSX only)

  homebrew:

    packages:

      ## Required dependencies

      - libevent

      ## The OSX version of OpenSSL is way too old

      - openssl

      ## OSX comes with zlib by default

      ## to use a newer zlib, pass the keg path to configure (like OpenSSL)

      #- zlib

      ## Optional dependencies

      - libscrypt

      ## Required build dependencies

      ## Tor needs pkg-config to find some dependencies at build time

      - pkg-config

      ## Optional build dependencies

      - ccache

      ## Conditional build dependencies

      ## Always installed, because manual brew installs are hard to get right

      - asciidoc

      - xmlto

## (OSX only) Use the default OSX image

## See https://docs.travis-ci.com/user/reference/osx#os-x-version

## Default is Xcode 9.4 on macOS 10.13 as of August 2018

#osx_image: xcode9.4

before_install:

  ## If we're on OSX, homebrew usually needs to be updated first

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update; fi

  ## We might be upgrading some useless packages, but that's better than missing an upgrade

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew upgrade; fi

install:

  ## If we're on OSX use brew to install ccache (ccache is automatically installed on Linux)

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install ccache; fi

  ## If we're on OSX, configure ccache (ccache is automatically installed and configured on Linux)

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export PATH="/usr/local/opt/ccache/libexec:$PATH"; fi

  ## If we're on OSX use brew to install required dependencies (for Linux, see the "apt:" section above)

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install libevent; fi

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install openssl; fi

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install pkg-config; fi

  ## macOS comes with zlib by default, so the homebrew install is keg-only

  # - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install zlib; fi

  ## If we're on OSX also install the optional dependencies

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install libscrypt; fi

  ## If we're on OSX, OpenSSL is keg-only, so tor 0.2.9 and later need to be configured --with-openssl-dir= to build

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then OPENSSL_OPTIONS=--with-openssl-dir=`brew --prefix openssl`; fi

  ## Install conditional features

  ## Install coveralls

  - if [[ "$COVERAGE_OPTIONS" != "" ]]; then pip install --user cpp-coveralls; fi

  ## If we're on OSX, and using asciidoc, install asciidoc

  - if [[ "$ASCIIDOC_OPTIONS" == "" ]] && [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install asciidoc; fi

  - if [[ "$ASCIIDOC_OPTIONS" == "" ]] && [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install xmlto; fi

  ## If we're on OSX, and using asciidoc, configure asciidoc

  - if [[ "$ASCIIDOC_OPTIONS" == "" ]] && [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export XML_CATALOG_FILES="/usr/local/etc/xml/catalog"; fi

  ##

  ## Finally, list installed package versions

  o Minor features (continuous integration):

    - Use the Travis Homebrew addon to install packages on macOS. The package

      list is the same, but the Homebrew addon does not do a `brew update` by

      default. Implements ticket 27738.