buildroot

zmqpp: bmp to version 4.1.2

Drop 0001-add-cstdlib-header-to-ensure-EXIT_FAILURE-presence.patch since
it's already upstream.

Rebase shared/static build patches - these look unnecessary if we switch
to cmake-package, however it seems to require the zmq package switches
to cmake-package as well since static library naming looks different,
which might be a problem for users.

Also set the minimum required version of gcc to 4.7.x since the code now
requires c++1x.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>