GCC up to 4.x defaults to C89. On our CI, we run the arm-none-eabi-gcc
version from Ubuntu 16.04 on Travis, and that's 4.9, so the gcc-arm
builds started failing on Travis when we introduced a C99 construct in
the configurations that we test on arm on Travis. Other builds, and
Jenkins CI, are not affected because they use GCC 5.x or newer.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>