travis: install the gcc-multilib to get the 32bit build OK

.travis.yml

@@ -6,7 +6,7 @@ notifications:
 before_script:
 # travis has changed to 64-bit and we require 32-bit compatibility libraries
   - sudo apt-get update
-  - "sudo apt-get -qq install clang libc6:i386 libgcc1:i386 gcc-4.6-base:i386 libstdc++5:i386 libstdc++6:i386 libsdl-dev || true"
+  - "sudo apt-get -qq install clang gcc-multilib libc6:i386 libgcc1:i386 gcc-4.6-base:i386 libstdc++5:i386 libstdc++6:i386 libsdl-dev || true"
   - "[ $RTT_TOOL_CHAIN = 'sourcery-arm' ] && curl -s https://sourcery.mentor.com/public/gnu_toolchain/arm-none-eabi/arm-2012.09-63-arm-none-eabi-i686-pc-linux-gnu.tar.bz2 | sudo tar xjf - -C /opt && export RTT_EXEC_PATH=/opt/arm-2012.09/bin && /opt/arm-2012.09/bin/arm-none-eabi-gcc --version || true"
   - "[ $RTT_TOOL_CHAIN = 'sourcery-mips' ] && curl -s https://sourcery.mentor.com/public/gnu_toolchain/mips-sde-elf/mips-2012.09-98-mips-sde-elf-i686-pc-linux-gnu.tar.bz2 | sudo tar xjf - -C /opt && export RTT_EXEC_PATH=/opt/mips-2012.09/bin && /opt/mips-2012.09/bin/mips-sde-elf-gcc --version || true"
   - "[ $RTT_TOOL_CHAIN = 'sourcery-ppc' ] && curl -s https://sourcery.mentor.com/public/gnu_toolchain/powerpc-eabi/freescale-2011.03-39-powerpc-eabi-i686-pc-linux-gnu.tar.bz2 | sudo tar xjf - -C /opt && export RTT_EXEC_PATH=/opt/freescale-2011.03/bin && /opt/freescale-2011.03/bin/powerpc-eabi-gcc --version || true"