img2: WebP support

Reviewed-by: Pascal Massimino <pascal.massimino@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/img2.c

@@ -74,6 +74,7 @@ static const IdStrMap img_tags[] = {
     { AV_CODEC_ID_EXR,        "exr"      },
     { AV_CODEC_ID_PICTOR,     "pic"      },
     { AV_CODEC_ID_V210X,      "yuv10"    },
+    { AV_CODEC_ID_WEBP,       "webp"     },
     { AV_CODEC_ID_XBM,        "xbm"      },
     { AV_CODEC_ID_XFACE,      "xface"    },
     { AV_CODEC_ID_XWD,        "xwd"      },