Ports failing with -fno-common with clang 9/gcc 9

[Dewayne Geraghty]

As -fno-common will become the default in gcc10/llvm11 per
https://lists.freebsd.org/pipermail/svn-src-stable-12/2020-April/004761.html

I thought I might share the list of ports that failed to build for
maintainers to be aware of using -fno-common:

archivers/arc
benchmarks/iozone
benchmarks/netperf
databases/gdbm
databases/libmemcached
databases/pgpool-II-40
databases/postgresql11-client
databases/postgresql11-server
devel/gnustep-make
devel/libunwind
graphics/freeglut
lang/erlang
lang/gnustep-base
lang/libobjc2
lang/yap-devel
mail/isoqlog
mail/spamilter
net-mgmt/argus3
net-mgmt/argus3-clients
net-mgmt/iftop
net-mgmt/nagios4
net/fping
net/isc-dhcp44-client
net/isc-dhcp44-relay
net/isc-dhcp44-server
net/socat
net/ss5
net/tableutil
ports-mgmt/pkg
security/gnupg1
security/openvas9-manager
security/openvpn-auth-ldap
security/ossec-hids-local
security/ossec-hids-server
security/snort
security/suricata
sysutils/LPRng
sysutils/logrotate
sysutils/lsof
sysutils/mpiexec
www/squidguard
www/webalizer

I'm sorry this is a small list but I only use 1488 ports.