It is usually require to done while building ffmpeg on freebsd.
Some script require it will be build using gcc44 so it does not complaint.
add following lines to start using gcc44.
replace number 44 with desired version. should do it.
.if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc44) CC=gcc44 CXX=g++44 CPP=cpp44 .endif