security/gvmd: fix plist

Missing @dir /var/lib makes testport complain.

security/gvmd/pkg-plist

@@ -52,3 +52,4 @@ share/man/man8/gvmd.8.gz
 @dir(gvm,gvm,750) /var/lib/gvm
 @dir(gvm,gvm,750) /var/run/gvm
 @dir(gvm,gvm,750) /var/log/gvm
+@dir /var/lib