Set bits_per_coded_sample when encoding Microsoft Video-1.

Fixes ticket #1193.

libavcodec/msvideo1enc.c

@@ -276,6 +276,7 @@ static av_cold int encode_init(AVCodecContext *avctx)
 
     avcodec_get_frame_defaults(&c->pic);
     avctx->coded_frame = (AVFrame*)&c->pic;
+    avctx->bits_per_coded_sample = 16;
 
     c->keyint = avctx->keyint_min;
     av_lfg_init(&c->rnd, 1);

tests/ref/vsynth1/msvideo1

-267a152a73cbc5ac4694a6e3b254be34 *./tests/data/vsynth1/msvideo1.avi
+37aa67b5928794534cb6a268d4adf48c *./tests/data/vsynth1/msvideo1.avi
 2162264 ./tests/data/vsynth1/msvideo1.avi
 c0665fac1bd896b6fe7fe0eead805bd5 *./tests/data/msvideo1.vsynth1.out.yuv
 stddev:   11.80 PSNR: 26.69 MAXDIFF:  151 bytes:  7603200/  7603200

tests/ref/vsynth2/msvideo1

-5dddbbd6616d9be4bc0fd0c9650bd9e3 *./tests/data/vsynth2/msvideo1.avi
+e70658b8b97eb4c7e63b2081c3a602de *./tests/data/vsynth2/msvideo1.avi
 1259308 ./tests/data/vsynth2/msvideo1.avi
 cd83ffcbc73573044e3aead3094229e5 *./tests/data/msvideo1.vsynth2.out.yuv
 stddev:    7.42 PSNR: 30.72 MAXDIFF:  123 bytes:  7603200/  7603200