Remove Eclipse build from the Travis job and cache the gcc archives

.travis.yml

@@ -1,36 +1,22 @@
 language: c
 
+os:
+  - linux
+  - osx
+
 cache:
   directories:
-    - $HOME/Library/Caches/Homebrew/Cask
+    # Cache for the gcc archives
+    - $HOME/gcc-cache/
 
-install: eclipse -noSplash
-         -application org.eclipse.equinox.p2.director
-         -repository http://gnuarmeclipse.sourceforge.net/updates
-         -installIUs ilg.gnuarmeclipse.managedbuild.cross.feature.group
-         -profileProperties org.eclipse.update.install.features=true
-
-before_script:
-  - tar -xf gcc-arm-none-eabi-7-2017-q4-major-*.tar.bz2
-  - export PATH=$PATH:$PWD/gcc-arm-none-eabi-7-2017-q4-major/bin
+install:
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then GCC_NAME="gcc-arm-none-eabi-7-2017-q4-major-mac.tar.bz2"; else GCC_NAME="gcc-arm-none-eabi-7-2017-q4-major-linux.tar.bz2"; fi
+  - if test ! -e $HOME/gcc-cache/$GCC_NAME ; then wget "https://developer.arm.com/-/media/Files/downloads/gnu-rm/7-2017q4/$GCC_NAME" -O $HOME/gcc-cache/$GCC_NAME ; fi
+  - tar -xf $HOME/gcc-cache/$GCC_NAME -C $HOME
+  - export PATH=$PATH:$HOME/gcc-arm-none-eabi-7-2017-q4-major/bin
 
 script:
-  - eclipse -noSplash -application org.eclipse.cdt.managedbuilder.core.headlessbuild -import $TRAVIS_BUILD_DIR/left/build -import $TRAVIS_BUILD_DIR/right/build -build all
   - make -C left clean && make -j2 -C left DEBUG=1
   - make -C left clean && make -j2 -C left DEBUG=0
   - make -C right clean && make -j2 -C right DEBUG=1
   - make -C right clean && make -j2 -C right DEBUG=0
-
-matrix:
-  include:
-    - os: linux
-      sudo: required
-      before_install:
-        - curl https://nixos.org/nix/install | sh && . ~/.nix-profile/etc/profile.d/nix.sh
-        - nix-env -i eclipse-cpp
-        - wget "https://developer.arm.com/-/media/Files/downloads/gnu-rm/7-2017q4/gcc-arm-none-eabi-7-2017-q4-major-linux.tar.bz2"
-    - os: osx
-      env: PATH="$PATH:/Applications/Eclipse CPP.app/Contents/MacOS"
-      before_install:
-        - brew cask install eclipse-cpp
-        - wget "https://developer.arm.com/-/media/Files/downloads/gnu-rm/7-2017q4/gcc-arm-none-eabi-7-2017-q4-major-mac.tar.bz2"