buildlink not bringing in proper parts?

[John Klos <john%ziaspace.com@localhost>]

Hi, all,

I wanted to compile ffmpeg3 with librtmp, which is made available through 
net/rtmpdump, but including net/rtmpdump/buildlink3.mk doesn't bring in 
/usr/local/lib/librtmp and friends. Can someone tell me what I'm missing?

Thanks,
John