For Travis CI - fix the condition as the env var may not be defined.

.travis.yml

@@ -46,7 +46,7 @@ before_install:
   - travis_retry sudo apt-get update -q -y
 install:
   - travis_retry sudo apt-get install -q -y --no-install-recommends libasound2-dev
-  - if [ $LINUX ] && [ $URHO3D_64BIT -eq 0 ]; then travis_retry sudo apt-get remove -q -y gvfs-daemons && travis_retry sudo apt-get install -q -y libxrandr-dev:i386 libglapi-mesa:i386 libgl1-mesa-glx:i386 libgl1-mesa-dev:i386 libxext-dev:i386 libxrender-dev:i386 g++-multilib && export CMAKE_PREFIX_PATH=/usr/lib/i386-linux-gnu; fi
+  - if [ $LINUX ] && [ "$URHO3D_64BIT" == "0" ]; then travis_retry sudo apt-get remove -q -y gvfs-daemons && travis_retry sudo apt-get install -q -y libxrandr-dev:i386 libglapi-mesa:i386 libgl1-mesa-glx:i386 libgl1-mesa-dev:i386 libxext-dev:i386 libxrender-dev:i386 g++-multilib && export CMAKE_PREFIX_PATH=/usr/lib/i386-linux-gnu; fi
   - if [ "$SITE_UPDATE_ON_MASTER_COMMIT" -o "$PACKAGE_UPLOAD" ]; then travis_retry sudo apt-get install -q -y --no-install-recommends doxygen graphviz; fi
   - if [ $WINDOWS ]; then travis_retry sudo apt-get install -q -y gcc-mingw-w64 gcc-mingw-w64-i686 gcc-mingw-w64-x86-64 g++-mingw-w64 g++-mingw-w64-i686 g++-mingw-w64-x86-64 binutils-mingw-w64 binutils-mingw-w64-i686 binutils-mingw-w64-x86-64 g++-multilib && export MINGW_PREFIX=/usr/bin/${ARCH}-w64-mingw32; fi
   - if [ $PACKAGE_UPLOAD ] && [ "$LINUX" -o "$RPI" ]; then travis_retry sudo apt-get install -q -y rpm; fi