tarvis: Unbreak build by ignoring lack of i386 arch in some repos.

For some reason, Travis now has Google Chrome PPA included in the builder
image, that lacks i386 arch, that leads to apt-get update error. So, ignore
it (this is not ideal as may lead to actual repo update failures to be missed,
leading to installation of old package, leading to weird errors; let's keep
that in mind).

.travis.yml

@@ -11,7 +11,7 @@ before_script:
 #  - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
   - sudo add-apt-repository -y ppa:terry.guo/gcc-arm-embedded
   - sudo dpkg --add-architecture i386
-  - sudo apt-get update -qq
+  - sudo apt-get update -qq || true
   - sudo apt-get install -y python3 gcc-multilib gcc-arm-none-eabi pkg-config libffi-dev libffi-dev:i386 qemu-system mingw32
   # For teensy build
   - sudo apt-get install realpath