travis-ci: change trusty image to xenial

Ubuntu Trusty reaches End of Life on April 30, 2019
Let us switch to xenial. Also, it simplifies mingw builds.
We do not need to add xenial mingw manually anymore

Signed-off-by: Ilya Shipitsin <chipitsine@gmail.com>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <20190311133620.18278-3-chipitsine@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18270.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

.travis.yml

@@ -1,5 +1,5 @@
 sudo: required
-dist: trusty
+dist: xenial
 
 os: linux
 
@@ -75,12 +75,7 @@ matrix:
 addons:
   apt:
     update: true
-    packages:
-      - liblzo2-dev
-      - libpam0g-dev
-      - liblz4-dev
-      - linux-libc-dev
-      - man2html
+    packages: [ liblzo2-dev, libpam0g-dev, liblz4-dev, linux-libc-dev, man2html, mingw-w64]
 
 cache:
   directories:

.travis/build-deps.sh

@@ -130,15 +130,6 @@ build_openssl () {
     fi
 }
 
-if [ ! -z ${CHOST+x} ]; then
-      #
-      # openvpn requires at least mingw-gcc-4.9, which is available at xenial repo
-      #
-      sudo apt-add-repository "deb http://archive.ubuntu.com/ubuntu xenial main universe"
-      sudo apt-get update
-      sudo apt-get -y install dpkg mingw-w64
-fi
-
 # Download and build crypto lib
 if [ "${SSLLIB}" = "openssl" ]; then
     download_openssl