net-mgmt/openbmp: fix build with GCC architectures

Building with GCC requires include sys/types.h in Server/src/Logger.h.

/wrkdirs/usr/ports/net-mgmt/openbmp/work/openbmp-0.14.0/Server/src/Logger.h:99:27: error: 'u_char' has not been declared

void setWidthFunction(u_char width);

PR: 239329
Approved by: pizzamig (maintainer), linimon (mentor)
Differential Revision: https://reviews.freebsd.org/D21026