For Travis CI - rpi-sysroot only contains strip down version in master.

Fall back to use Raspbian Wheezy again as Jessie has problem to build SDL library. However, the new Wheezy sysroot is now preinstalled with PulseAudio development library.
[ci skip]

.travis.yml

@@ -291,7 +291,7 @@ matrix:
     - compiler: gcc-armeabi-v7a-with-NEON-shared
       env: URHO3D_LIB_TYPE=SHARED RPI_ABI='armeabi-v7a with NEON'
 before_script:
-  - git clone --depth 1 https://github.com/raspberrypi/tools.git rpi-tools && export RPI_PREFIX=$(pwd)/rpi-tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf && git clone --depth 1 --branch strip https://github.com/urho3d/rpi-sysroot.git && export RPI_SYSROOT=$(pwd)/rpi-sysroot && for f in $RPI_PREFIX-{gcc,g++}; do touch -d "2015-01-01 00:00:00 +0800" $f; done
+  - git clone --depth 1 https://github.com/raspberrypi/tools.git rpi-tools && export RPI_PREFIX=$(pwd)/rpi-tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf && git clone --depth 1 https://github.com/urho3d/rpi-sysroot.git && export RPI_SYSROOT=$(pwd)/rpi-sysroot && for f in $RPI_PREFIX-{gcc,g++}; do touch -d "2015-01-01 00:00:00 +0800" $f; done
   - export TRAVIS_COMMIT=$TRAVIS_COMMIT~
   - export TAG=$(git describe --exact-match $TRAVIS_COMMIT 2>/dev/null); if [[ $TAG =~ [[:digit:]]+\.[[:digit:]]+ ]]; then export RELEASE_TAG=$TAG; fi
   - export COMMIT_MESSAGE=$(git log --format=%B -n 1 $TRAVIS_COMMIT)