Fixes: http://autobuild.buildroot.net/results/faf/faf0bb00fccb1350afaef55f6cf14c11a5f5dc3c/ http://autobuild.buildroot.net/results/8d2/8d279baa4c8bffbb01f897119092c7b736942df4/ http://autobuild.buildroot.net/results/4d3/4d3dea604da9a5a1e7fe20548813f8de474ae33f/ http://autobuild.buildroot.net/results/fd6/fd602617839817352763e51754553960b7f795ac/ And many more. Libzmq uses C++ standard library features, so users of it should link against that as well when statically linking. Add it to Libs.private so users using pkg-config automatically gets the correct linker flags. Patch is upstream: https://github.com/zeromq/libzmq/pull/1398 Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
