norm: fix build with gcc 7.x

This commit adds a patch to the norm package that fixes the build with
gcc 7.x. Many thanks to Romain Naour for pointing out the solution to
this C++ build problem.

Fixes:

  http://autobuild.buildroot.net/results/c79dc84cdc34d62199099eb4438b1aed3e7459bb/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
[Thomas: add information that the patch has been submitted upstream
and accepted.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>