package/zmqpp: add patch to fix build issue

Add a patch from upstream to fix build error:
  error: no match for 'operator<<'

Fixes:
http://autobuild.buildroot.net/results/ed4508a00663b03632a4eb9411ba05852d02fd88/



Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>