configure: add optional zlib dependency to avformat

id3v2 code is compiled unconditionally and uses zlib when available.
Signed-off-by: James Almer <jamrial@gmail.com>

configure

@@ -3318,7 +3318,7 @@ avdevice_suggest="libm"
 avfilter_deps="avutil"
 avfilter_suggest="libm"
 avformat_deps="avcodec avutil"
-avformat_suggest="libm network"
+avformat_suggest="libm network zlib"
 avresample_deps="avutil"
 avresample_suggest="libm"
 avutil_suggest="clock_gettime libm libdrm libmfx opencl user32 vaapi videotoolbox corefoundation corevideo coremedia wincrypt"