[ci] Add scons env in CI

.travis.yml

@@ -7,7 +7,7 @@ before_script:
 # travis has changed to 64-bit and we require 32-bit compatibility libraries
   - sudo apt-get update
   # clang
-  - "sudo apt-get -qq install gcc-multilib libc6:i386 libgcc1:i386 gcc-4.6-base:i386 libstdc++5:i386 libstdc++6:i386 libsdl-dev || true"
+  - "sudo apt-get -qq install gcc-multilib libc6:i386 libgcc1:i386 gcc-4.6-base:i386 libstdc++5:i386 libstdc++6:i386 libsdl-dev scons || true"
   # - sudo apt-get -qq install gcc-arm-none-eabi
   # - "[ $RTT_TOOL_CHAIN = 'sourcery-arm' ] && export RTT_EXEC_PATH=/usr/bin && arm-none-eabi-gcc --version || true"
   # - "[ $RTT_TOOL_CHAIN = 'sourcery-arm' ] && curl -s https://sourcery.mentor.com/public/gnu_toolchain/arm-none-eabi/arm-2014.05-28-arm-none-eabi-i686-pc-linux-gnu.tar.bz2 | sudo tar xjf - -C /opt && export RTT_EXEC_PATH=/opt/arm-2014.05/bin && /opt/arm-2014.05/bin/arm-none-eabi-gcc --version || true"