ci: switch linux/sitl compiler to 4.9

.travis.yml

@@ -6,12 +6,6 @@ cache:
     - $HOME/opt
 
 addons:
-  apt:
-    sources:
-    - ubuntu-toolchain-r-test
-    packages:
-    - g++-4.8
-    - gcc-4.8
   coverity_scan:
     project:
       name: "diydrones/ardupilot"

Tools/scripts/configure-ci.sh

@@ -1,10 +1,10 @@
 #!/bin/bash
 # Install dependencies and configure the environment for CI build testing
 
-set -ev
+set -ex
 
 PKGS="build-essential gawk ccache genromfs libc6-i386 \
-      python-argparse python-empy python-serial zlib1g-dev"
+      python-argparse python-empy python-serial zlib1g-dev gcc-4.9 g++-4.9"
 
 ARM_ROOT="gcc-arm-none-eabi-4_9-2015q3"
 ARM_TARBALL="$ARM_ROOT-20150921-linux.tar.bz2"
@@ -12,8 +12,11 @@ ARM_TARBALL="$ARM_ROOT-20150921-linux.tar.bz2"
 RPI_ROOT="master"
 RPI_TARBALL="$RPI_ROOT.tar.gz"
 
+sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
 sudo apt-get -qq -y update
 sudo apt-get -qq -y install $PKGS
+sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 90 \
+    --slave /usr/bin/g++ g++ /usr/bin/g++-4.9
 
 pushd $HOME