upgrade ccache / convert to generic travis language

.travis.yml

@@ -1,4 +1,4 @@
-language: cpp
+language: generic
 
 git:
   depth: 10
@@ -25,7 +25,7 @@ matrix:
     - os: linux
       sudo: false
       compiler: ": clang"
-      env: JOBS=8 MASON_PUBLISH=true _CXX="ccache clang++-3.8 -Qunused-arguments" _CC="clang-3.8" TRIGGER=true
+      env: JOBS=8 MASON_PUBLISH=true CXX="ccache clang++-3.8 -Qunused-arguments" CC="clang-3.8" TRIGGER=true
       addons:
         apt:
           sources: [ 'ubuntu-toolchain-r-test']
@@ -33,7 +33,7 @@ matrix:
     - os: linux
       sudo: false
       compiler: ": clang-coverage"
-      env: JOBS=8 COVERAGE=true _CXX="ccache clang++-3.8 -Qunused-arguments" _CC="clang-3.8"
+      env: JOBS=8 COVERAGE=true CXX="ccache clang++-3.8 -Qunused-arguments" CC="clang-3.8"
       addons:
         apt:
           sources: [ 'ubuntu-toolchain-r-test']
@@ -42,7 +42,7 @@ matrix:
       compiler: ": clang-osx"
       # https://docs.travis-ci.com/user/languages/objective-c/#Supported-OS-X-iOS-SDK-versions
       osx_image: xcode7.3 # upgrades clang from 6 -> 7
-      env: JOBS=4 MASON_PUBLISH=true _CXX="ccache clang++ -Qunused-arguments"
+      env: JOBS=4 MASON_PUBLISH=true CXX="ccache clang++ -Qunused-arguments"
 
 before_install:
  # workaround travis rvm bug
@@ -51,8 +51,6 @@ before_install:
    if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
      rvm get head || true
    fi
- - if [[ ${_CXX:-false} != false ]]; then export CXX=${_CXX}; fi
- - if [[ ${_CC:-false} != false ]]; then export CC=${_CC}; fi
  - source scripts/travis-common.sh
  - export PYTHONUSERBASE=$(pwd)/mason_packages/.link
  - export PATH=${PREFIX}/bin:$(pwd)/mason_packages/.link/bin:${PYTHONUSERBASE}/bin:${PATH}

bootstrap.sh

@@ -48,7 +48,7 @@ ICU_VERSION="55.1"
 
 function install_mason_deps() {
     FAIL=0
-    install ccache 3.2.4 &
+    install ccache 3.3.0 &
     install jpeg_turbo 1.5.0 libjpeg &
     install libpng 1.6.24 libpng &
     install libtiff 4.0.6 libtiff &