I might be too late, but I suppose you should swap pkg-config --cflags --libs opencv
and
&& '${file_path}/${file_base_name}''s position, since pkg-config
part is used in compilation, and the && '${file_path}/${file_base_name}' part seems to be the execution part.
"cmd": ["bash", "-c", "g++ -ggdb '${file}' -o '${file_path}/${file_base_name}' pkg-config --cflags --libs opencv
&& '${file_path}/${file_base_name}' "]
If you're interested, I've created my own build system of it here: http://subokita.com/2013/04/21/configuring-sublime-to-work-with-opencv-on-mac/