build: try installing toolchain from develop developer.arm.com

.travis.yml

@@ -23,8 +23,6 @@ addons:
     packages:
     - build-essential
     - gcc-multilib
-    - gcc-arm-none-eabi
-    - libnewlib-arm-none-eabi
     - libusb-1.0-0-dev
     - libudev-dev
     - python3
@@ -41,6 +39,11 @@ install:
     - pip3 install --user ecdsa mnemonic protobuf requests
     - pip3 install --user git+https://github.com/trezor/python-trezor@master
 
+before_script:
+    - test "$GOAL" != "stm32" || wget https://developer.arm.com/-/media/Files/downloads/gnu-rm/6-2017q2/gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2
+    - test "$GOAL" != "stm32" || tar xfj gcc-arm-none-eabi-6-2017-q2-update-linux.tar.bz2
+    - test "$GOAL" != "stm32" || export PATH=$PATH:$PWD/gcc-arm-none-eabi-6-2017-q2-update/bin
+
 script:
   - test "$GOAL" != "stm32" || make vendorheader
   - test "$GOAL" != "stm32" || make build_cross