Travis: add Windows build via MXE

Tests are disabled for MXE since they fail to build. Problem is lack of proper main, but fix might break them on other platforms.
Since we don't have many automated tests anyway better to disable it for now when it's built using MXE.

.travis.mxe

@@ -0,0 +1,27 @@
+#!/bin/sh
+
+# Add MXE repository and key
+echo "deb http://pkg.mxe.cc/repos/apt/debian wheezy main" \
+    | sudo tee /etc/apt/sources.list.d/mxeapt.list
+
+sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys D43A795B73B16ABE9643FE1AFD8FFF16DB45C6AB
+
+# Install needed packages
+sudo apt-get update -qq
+
+sudo apt-get install -qq \
+mxe-$MXE_TARGET-gcc \
+mxe-$MXE_TARGET-boost \
+mxe-$MXE_TARGET-zlib \
+mxe-$MXE_TARGET-sdl2 \
+mxe-$MXE_TARGET-sdl2-gfx \
+mxe-$MXE_TARGET-sdl2-image \
+mxe-$MXE_TARGET-sdl2-mixer \
+mxe-$MXE_TARGET-sdl2-ttf \
+mxe-$MXE_TARGET-ffmpeg \
+mxe-$MXE_TARGET-qt \
+mxe-$MXE_TARGET-qtbase
+
+# alias for CMake
+sudo mv /usr/bin/cmake /usr/bin/cmake.orig
+sudo ln -s /usr/lib/mxe/usr/bin/$MXE_TARGET-cmake /usr/bin/cmake

.travis.yml

@@ -6,13 +6,14 @@ dist: trusty
 sudo: required
 
 before_install:
-  - if [[ $TRAVIS_OS_NAME == 'linux' ]]; then . .travis.linux; fi
-  - if [[ $TRAVIS_OS_NAME == 'osx' ]]; then . .travis.osx; fi
+  - if [[ $VCMI_PLATFORM == 'linux' ]]; then . .travis.linux; fi
+  - if [[ $VCMI_PLATFORM == 'mac' ]]; then . .travis.osx; fi
+  - if [[ $VCMI_PLATFORM == 'mxe' ]]; then . .travis.mxe; fi
 
 before_script:
   - mkdir build
   - cd build
-  - cmake -G "Unix Makefiles" ..
+  - cmake -G "Unix Makefiles" .. $VCMI_CMAKE_FLAGS
 
 script:
   - if [[ $TRAVIS_OS_NAME == 'osx' ]]; then cd ..; xcodebuild -project osx/osx-vcmibuilder/vcmibuilder.xcodeproj/ -configuration Release CONFIGURATION_BUILD_DIR=..; cd build; fi
@@ -27,17 +28,21 @@ matrix:
   include:
     - os: linux
       compiler: clang
-      env: REAL_CC=clang-3.4 REAL_CXX=clang++-3.4 PACKAGE=clang-3.4 SUPPORT=libstdc++-4.8-dev
+      env: VCMI_PLATFORM='linux' REAL_CC=clang-3.4 REAL_CXX=clang++-3.4 PACKAGE=clang-3.4 SUPPORT=libstdc++-4.8-dev
     - os: linux
       compiler: clang
-      env: REAL_CC=clang-3.5 REAL_CXX=clang++-3.5 PACKAGE=clang-3.5 SUPPORT=libstdc++-4.8-dev
+      env: VCMI_PLATFORM='linux' REAL_CC=clang-3.5 REAL_CXX=clang++-3.5 PACKAGE=clang-3.5 SUPPORT=libstdc++-4.8-dev
     - os: linux
       compiler: clang
-      env: REAL_CC=clang-3.6 REAL_CXX=clang++-3.6 PACKAGE=clang-3.6 SUPPORT=libstdc++-4.8-dev
+      env: VCMI_PLATFORM='linux' REAL_CC=clang-3.6 REAL_CXX=clang++-3.6 PACKAGE=clang-3.6 SUPPORT=libstdc++-4.8-dev
     - os: linux
       compiler: gcc
-      env: REAL_CC=gcc-4.8   REAL_CXX=g++-4.8     PACKAGE=g++-4.8   SUPPORT=
+      env: VCMI_PLATFORM='linux' REAL_CC=gcc-4.8   REAL_CXX=g++-4.8     PACKAGE=g++-4.8   SUPPORT=
+    - os: linux
+      env: VCMI_PLATFORM='mxe' MXE_TARGET=i686-w64-mingw32.shared VCMI_CMAKE_FLAGS='-DENABLE_TEST=0'
+      sudo: required
     - os: osx
+      env: VCMI_PLATFORM='mac'
 
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