run_depends for p5-Net-Netmask in Makefile

[Fbsd8]

The security/ppars port currently has this statement

RUN_DEPENDS= p5-Net-Netmask>=0:${PORTSDIR}/net-mgmt/p5-Net-Netmask

Here is the problem, if "pkg install p5-Net-Netmask" is done prier to 
make install on the port, the port checks the hosts ports tree for
/net-mgmt/p5-Net-Netmask and recompiles it any way.

Is there any way to code RUN_DEPENDS to check if "p5-Net-Netmask" is 
already installed?