CI: Install g++-multilib for win32

Signed-off-by: falkTX <falktx@falktx.com>

.travis/install.sh

@@ -9,7 +9,7 @@ if [ "${TARGET}" = "linux" ]; then
     sudo apt-get install -y pkg-config libfreetype6-dev libx11-dev libxcomposite-dev libxrender-dev libxcursor-dev libasound2-dev libgl1-mesa-dev libglu1-mesa-dev
 
 elif [ "${TARGET}" = "win32" ]; then
-    sudo apt-get install -y mingw-w64 binutils-mingw-w64-i686 g++-mingw-w64-i686 wine32-development-tools
+    sudo apt-get install -y mingw-w64 binutils-mingw-w64-i686 g++-mingw-w64-i686 g++-multilib wine32-development-tools
 
 elif [ "${TARGET}" = "win64" ]; then
     sudo apt-get install -y mingw-w64 binutils-mingw-w64-x86-64 g++-mingw-w64-x86-64 wine64-development-tools