ci: remove travis

(cherry picked from commit 6fc946e8)

.travis.yml

-# Travis-CI Build for libgit2
-# see travis-ci.org for details
-
-language: c
-
-os:
-  - linux
-  - osx
-
-compiler:
-  - gcc
-  - clang
-
-# Settings to try
-env:
- global:
-  - secure: "YnhS+8n6B+uoyaYfaJ3Lei7cSJqHDPiKJCKFIF2c87YDfmCvAJke8QtE7IzjYDs7UFkTCM4ox+ph2bERUrxZbSCyEkHdjIZpKuMJfYWja/jgMqTMxdyOH9y8JLFbZsSXDIXDwqBlC6vVyl1fP90M35wuWcNTs6tctfVWVofEFbs="
-  - GITTEST_INVASIVE_FS_SIZE=1
-  - SKIP_APT=1
-  - PKG_CONFIG_PATH=/usr/local/opt/openssl/lib/pkgconfig
- matrix:
-  - CMAKE_OPTIONS="-DTHREADSAFE=ON -DENABLE_TRACE=ON -DCMAKE_BUILD_TYPE=Release"
-  - CMAKE_OPTIONS="-DTHREADSAFE=OFF -DBUILD_EXAMPLES=ON"
-
-dist: trusty
-osx_image: xcode8.3
-sudo: false
-
-addons:
- apt:
-  sources:
-   - sourceline: 'deb https://dl.bintray.com/libgit2/ci-dependencies trusty libgit2deps'
-     key_url: 'https://bintray.com/user/downloadSubjectPublicKey?username=bintray'
-  packages:
-   cmake
-   curl
-   libcurl3
-   libcurl3-gnutls
-   libcurl4-gnutls-dev
-   libssh2-1-dev
-   openssh-client
-   openssh-server
-   valgrind
-
-matrix:
- fast_finish: true
- exclude:
-   - os: osx
-     compiler: gcc
- include:
-   - compiler: gcc
-     env:
-       - LEAK_CHECK=valgrind
-         CMAKE_OPTIONS="-DBUILD_CLAR=ON -DBUILD_EXAMPLES=OFF -DDEBUG_POOL=ON -DCMAKE_BUILD_TYPE=Debug"
-     os: linux
-     dist: trusty
-   - compiler: gcc
-     if: type = cron
-     env:
-       - CMAKE_OPTIONS="-DBUILD_CLAR=ON -DCMAKE_BUILD_TYPE=Debug"
-         COVERITY=1
-     os: linux
-
-install:
-  - if [ -f ./ci/setup-${TRAVIS_OS_NAME}.sh ]; then ./ci/setup-${TRAVIS_OS_NAME}.sh; fi
-
-# Run the Build script and tests
-script:
- - mkdir build
- - cd build
- - if [ -n "$COVERITY" ]; then ../ci/coverity.sh; fi
- - if [ -z "$COVERITY" ]; then ../ci/build.sh && ../ci/test.sh; fi
-
-# Only watch the development and master branches
-branches:
- only:
-   - master
-   - /^maint.*/
-
-# Notify development list when needed
-notifications:
- irc:
-  channels:
-    - irc.freenode.net#libgit2
-  on_success: change
-  on_failure: always
-  use_notice: true
-  skip_join: true
- campfire:
-  on_success: always
-  on_failure: always
-  rooms:
-   - secure: "sH0dpPWMirbEe7AvLddZ2yOp8rzHalGmv0bYL/LIhVw3JDI589HCYckeLMSB\n3e/FeXw4bn0EqXWEXijVa4ijbilVY6d8oprdqMdWHEodng4KvY5vID3iZSGT\nxylhahO1XHmRynKQLOAvxlc93IlpVW38vQfby8giIY1nkpspb2w="