[travis] add arm gcc 9 to build tests (#4323)

.travis.yml

@@ -112,6 +112,10 @@ jobs:
 #      os: linux
 #      compiler: gcc
 #      script: .travis/script.sh
+    - env: BUILD_TARGET="arm-gcc-9"
+      os: linux
+      compiler: gcc
+      script: .travis/script.sh
     - env: BUILD_TARGET="posix" CC="gcc-5" CXX="g++-5"
       os: linux
       compiler: gcc

.travis/before_install.sh

@@ -115,6 +115,13 @@ cd /tmp || die
         arm-none-eabi-gcc --version || die
     }
 
+    [ $BUILD_TARGET != arm-gcc-9 ] || {
+        wget https://developer.arm.com/-/media/Files/downloads/gnu-rm/9-2019q4/RC2.1/gcc-arm-none-eabi-9-2019-q4-major-x86_64-linux.tar.bz2 || die
+        tar xjf gcc-arm-none-eabi-9-2019-q4-major-x86_64-linux.tar.bz2 || die
+        export PATH=/tmp/gcc-arm-none-eabi-9-2019-q4-major/bin:$PATH || die
+        arm-none-eabi-gcc --version || die
+    }
+
     [ $BUILD_TARGET != posix-32-bit -a $BUILD_TARGET != posix-mtd ] || {
         sudo apt-get install g++-multilib || die
     }

.travis/script.sh

@@ -389,6 +389,21 @@ build_samr21() {
     build_samr21
 }
 
+[ $BUILD_TARGET != arm-gcc-9 ] || {
+    export PATH=/tmp/gcc-arm-none-eabi-9-2019-q4-major/bin:$PATH || die
+
+    build_cc1352
+    build_cc2538
+    build_cc2650
+    build_cc2652
+    build_kw41z
+    build_nrf52811
+    build_nrf52833
+    build_nrf52840
+    build_qpg6095
+    build_samr21
+}
+
 [ $BUILD_TARGET != posix ] || {
     git checkout -- . || die
     git clean -xfd || die