Use more recent toolchain from ARM

.travis.yml

@@ -45,14 +45,30 @@
           sources:
             - ubuntu-toolchain-r-test
           packages:
-            - gcc-arm-none-eabi
+      env:
+        - MATRIX_EVAL="CC=arm-none-eabi-gcc && CXX=arm-none-eabi-g++"
+        - GCC_URL="https://developer.arm.com/-/media/Files/downloads/gnu-rm/9-2019q4/gcc-arm-none-eabi-9-2019-q4-major-x86_64-linux.tar.bz2?revision=108bd959-44bd-4619-9c19-26187abf5225&la=en&hash=E788CE92E5DFD64B2A8C246BBA91A249CB8E2D2D"
       cache:
         directories:
       git:
         depth: false
         quiet: true
 
+      before_install:
+        - eval "${MATRIX_EVAL}"
+
       install:
+        - pushd .
+        - cd ~ 
+        - mkdir arm-gcc-toolchain
+        - wget -O $HOME/arm-gcc-toolchain/gcc.tar.bz2 $GCC_URL
+        - cd arm-gcc-toolchain
+        - tar -jxf gcc.tar.bz2 --strip=1
+        - popd
+        - export PATH=$HOME/arm-gcc-toolchain/bin:$PATH      
+
+      before_script:
+        - arm-none-eabi-gcc --version
 
       script:
         - echo "building knx-cc1310"