Openbsd build fixes 2

Fix error in tcpconns.c introduced in df46cd0 (only affecting openbsd/netbsd) and include vmmeter.h for struct vmtotal (see http://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/sysutils/collectd/patches/patch-src_memory_c?rev=1.1&content-type=text/x-cvsweb-markup for downstream patch)