Tries to build emscripten on linux as macosx fails

.travis.yml

@@ -19,6 +19,8 @@ matrix:
       env: BUILD_TYPE=ANDROID
     - os: osx
       env: BUILD_TYPE=Emscripten
+    - os: linux
+      env: BUILD_TYPE=Emscripten
 
 android:
   components:
@@ -72,9 +74,13 @@ before_install:
       export SDL2DIR="$TRAVIS_BUILD_DIR/thirdparty/SDL2";
     fi
 # Building for Emscripten here
-  - if [ "$BUILD_TYPE" == "Emscripten" ]; then
+  - if [ "$BUILD_TYPE" == "Emscripten" ] && [ "$TRAVIS_OS_NAME" == "osx" ]; then
       brew install emscripten && export LLVM=/usr/local/opt/emscripten/libexec/llvm/bin && emcc;
     fi
+  - if [ "$BUILD_TYPE" == "Emscripten" ] && [ "$TRAVIS_OS_NAME" == "linux" ]; then
+      git clone --depth 1 https://github.com/urho3d/emscripten-sdk.git && emscripten-sdk/emsdk activate --build=Release sdk-master-64bit && source emscripten-sdk/emsdk_env.sh &&
+      export PATH=$(whereis -b ccache |grep -o '\S*lib\S*'):$PATH; for f in $EMSCRIPTEN/{emcc,em++}; do touch -d "2015-09-01 00:00:00 +0800" $f; done;
+    fi
 
 install:
   - if [ "$TRAVIS_OS_NAME" == "linux" ]; then