Build issue: ld: symbol(s) not found for architecture x86_64

[eladg]

elad-hb2:rendersound $ ./waf configure build install
Setting top to                           : /Users/elad/Documents/rendersound 
Setting out to                           : /Users/elad/Documents/rendersound/build 
Checking for 'gcc' (c compiler)          : /usr/bin/gcc 
Checking for library gd                  : yes 
Checking for program pkg-config          : /usr/local/bin/pkg-config 
Checking for 'libavcodec'                : yes 
Checking for 'libavformat'               : yes 
'configure' finished successfully (0.142s)
Waf: Entering directory `/Users/elad/Documents/rendersound/build'
[5/5] cprogram: build/src/rendersound.c.1.o build/src/soundrenderer.c.1.o build/extern/ffsnd/src/ffsndin.c.1.o build/extern/ffsnd/src/ffsndutil.c.1.o -> build/rendersound
Undefined symbols for architecture x86_64:
  "_av_rescale_q", referenced from:
      _ffsndin_seek in ffsndin.c.1.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Waf: Leaving directory `/Users/elad/Documents/rendersound/build'
Build failed
 -> task in 'rendersound' failed (exit status 1): 
  {task 4380362000: cprogram rendersound.c.1.o,soundrenderer.c.1.o,ffsndin.c.1.o,ffsndutil.c.1.o -> rendersound}
['/usr/bin/gcc', 'src/rendersound.c.1.o', 'src/soundrenderer.c.1.o', 'extern/ffsnd/src/ffsndin.c.1.o', 'extern/ffsnd/src/ffsndutil.c.1.o', '-o', '/Users/elad/Documents/rendersound/build/rendersound', '-L/usr/local/Cellar/ffmpeg/2.1.3/lib', '-L/usr/local/Cellar/ffmpeg/2.1.3/lib', '-lgd', '-lavcodec', '-lavformat']