Add ccache to travis

.travis.yml

@@ -5,6 +5,7 @@ env:
  - ARCH="x86_64"
 compiler:
  - gcc
+cache: ccache
 addons:
   apt:
     sources:
@@ -15,8 +16,8 @@ addons:
       - g++-5
       - gcc-5
 install:
- - if [ "$CXX" = "g++" ]; then export CXX="g++-5" CC="gcc-5"; fi
- - if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.7" CC="clang-3.7"; fi
+ - if [ "$CXX" = "g++" ]; then export CXX="ccache g++-5" CC="ccache gcc-5"; fi
+ - if [ "$CXX" = "clang++" ]; then export CXX="ccache clang++-3.7" CC="ccache clang-3.7"; fi
  - wget --no-check-certificate https://cmake.org/files/v3.4/cmake-3.4.0-Linux-x86_64.tar.gz
  - tar -xf cmake-3.4.0-Linux-x86_64.tar.gz
  - wget http://www.llvm.org/releases/3.7.0/llvm-3.7.0.src.tar.xz 
@@ -25,8 +26,8 @@ install:
  - cd $TRAVIS_BUILD_DIR/llvm-3.7.0.src/build && $TRAVIS_BUILD_DIR/cmake-3.4.0-Linux-x86_64/bin/cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/tmp/LLVM37 -DLLVM_TARGETS_TO_BUILD="X86" ..
  - cd $TRAVIS_BUILD_DIR/llvm-3.7.0.src/build && make install
 script:
- - if [ "$CXX" = "g++" ]; then export CXX="g++-5" CC="gcc-5"; fi
- - if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.7" CC="clang-3.7"; fi
+ - if [ "$CXX" = "g++" ]; then export CXX="ccache g++-5" CC="ccache gcc-5"; fi
+ - if [ "$CXX" = "clang++" ]; then export CXX="ccache clang++-3.7" CC="ccache clang-3.7"; fi
  - mkdir $TRAVIS_BUILD_DIR/build
  - cd $TRAVIS_BUILD_DIR/build && $TRAVIS_BUILD_DIR/cmake-3.4.0-Linux-x86_64/bin/cmake -DCMAKE_BUILD_TYPE=Release -DLLVM_DIR=/tmp/LLVM37/share/llvm/cmake -G "Unix Makefiles" -DLLVM_JIT=ON ..
  - cd $TRAVIS_BUILD_DIR/build && make