support/script/check-bin-arch: ignore /usr/share

support/script/check-bin-arch: ignore /usr/share

/usr/share normally should not contain binaries executable for the
target platform. However, it might contain ELF binaries for other
platforms, such as firmware files installed by Qemu or
pru-software-support.

Instead of special-casing each package, let's simply ignore /usr/share.

Fixes:

  http://autobuild.buildroot.net/results/6f3fea9f6adaef1573fbb0dd6903b5d99e470610/
  (pru-software-support)

  http://autobuild.buildroot.net/results/fe8892bc22a03299fc41e30bfea5e42166838f88/
  (qemu)

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