toolchain-external: bump Linaro ARM to 2014.05

The major changes are: switch to gcc 4.9 instead of 4.8, and switch to
glibc 2.19 instead of glibc 2.18.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>