This fixes error handling for BeOS, removing the need for some ifdefs.

AVERROR_ defines are moved to avcodec.h as they are needed in there as well. Feel free to move that to avutil/common.h.
Bumped up avcodec/format version numbers as though it's binary compatible we will want to rebuild apps as error values changed.
Please from now on use return AVERROR(EFOO) instead of the ugly return -EFOO in your code.
This also removes the need for berrno.h.

Originally committed as revision 7965 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/gifdec.c

@@ -87,7 +87,7 @@ static int gif_read_image(GifState *s)
     /* verify that all the image is inside the screen dimensions */
     if (left + width > s->screen_width ||
         top + height > s->screen_height)
-        return -EINVAL;
+        return AVERROR(EINVAL);
 
     /* build the palette */
     n = (1 << bits_per_pixel);