Small configure fix for Darwin / Mac OS X.

This option tells linker to look for local libraries first. If you have
a shared livavcodec/libavformat in the library path and try to build a
static build, the linker will find the shared library first and link
with it.
patch by (Roine Gustafsson <roine users.sourceforge net>)

Originally committed as revision 3793 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -265,7 +265,7 @@ SHFLAGS="-dynamiclib"
 extralibs=""
 darwin="yes"
 strip="strip -x"
-LDFLAGS="-Wl,-d"
+LDFLAGS="-Wl,-d,-search_paths_first"
 FFSLDFLAGS=-Wl,-bind_at_load
 ;;
 MINGW32*)