lavc/rawdec: Use AV_PIX_FMT_PAL8 for raw 1 bpp video in AVI

 From
https://msdn.microsoft.com/en-us/library/windows/desktop/dd318229%28v=vs.85%29.aspx:

"If biCompression equals BI_RGB and the bitmap uses 8 bpp or less, the
bitmap has a color table immediatelly following the BITMAPINFOHEADER
structure. The color table consists of an array of RGBQUAD values. The
size of the array is given by the biClrUsed member. If biClrUsed is
zero, the array contains the maximum number of colors for the given
bitdepth; that is, 2^biBitCount colors."

Nothing about "monochrome" here. Unfortunately, pal8 to monow conversion
seems a bit flaky, but that's another story.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/raw.c

@@ -282,7 +282,7 @@ unsigned int avcodec_pix_fmt_to_codec_tag(enum AVPixelFormat fmt)
 }
 
 const PixelFormatTag avpriv_pix_fmt_bps_avi[] = {
-    { AV_PIX_FMT_MONOWHITE, 1 },
+    { AV_PIX_FMT_PAL8,    1 },
     { AV_PIX_FMT_PAL8,    2 },
     { AV_PIX_FMT_PAL8,    4 },
     { AV_PIX_FMT_PAL8,    8 },

tests/ref/vsynth/vsynth1-bpp1

 3e5e0f4afb3a0350440e86b1ea56cec9 *tests/data/fate/vsynth1-bpp1.avi
 640452 tests/data/fate/vsynth1-bpp1.avi
-ccef5f5d5b0392f1d01c200499dac657 *tests/data/fate/vsynth1-bpp1.out.rawvideo
-stddev:   97.30 PSNR:  8.37 MAXDIFF:  237 bytes:  7603200/  7603200
+853694f3c1aa3ef3807ab1fccbeefe7b *tests/data/fate/vsynth1-bpp1.out.rawvideo
+stddev:   84.44 PSNR:  9.60 MAXDIFF:  221 bytes:  7603200/  7603200

tests/ref/vsynth/vsynth2-bpp1

 771437c9038b44f4e2d4ff764c1c3821 *tests/data/fate/vsynth2-bpp1.avi
 640452 tests/data/fate/vsynth2-bpp1.avi
-ba70b5aebc786e625af6bd7f7ec82717 *tests/data/fate/vsynth2-bpp1.out.rawvideo
-stddev:   81.63 PSNR:  9.89 MAXDIFF:  237 bytes:  7603200/  7603200
+94261fc8aa20130cbd4361e15b742ef7 *tests/data/fate/vsynth2-bpp1.out.rawvideo
+stddev:   70.29 PSNR: 11.19 MAXDIFF:  221 bytes:  7603200/  7603200

tests/ref/vsynth/vsynth3-bpp1

 a5e6d1eff2f6fc3bba31e3bb8753b905 *tests/data/fate/vsynth3-bpp1.avi
 15352 tests/data/fate/vsynth3-bpp1.avi
-75e8ee0c0b0ada4515455d9f29377a16 *tests/data/fate/vsynth3-bpp1.out.rawvideo
-stddev:   97.70 PSNR:  8.33 MAXDIFF:  248 bytes:    86700/    86700
+79076b5fc43ee2a2284c0cde991d21f3 *tests/data/fate/vsynth3-bpp1.out.rawvideo
+stddev:   84.88 PSNR:  9.55 MAXDIFF:  232 bytes:    86700/    86700

tests/ref/vsynth/vsynth_lena-bpp1

 d53d08c755ffde5fca744f0f941bfcb1 *tests/data/fate/vsynth_lena-bpp1.avi
 640452 tests/data/fate/vsynth_lena-bpp1.avi
-9a66df9009670b0a593d889975246c00 *tests/data/fate/vsynth_lena-bpp1.out.rawvideo
-stddev:   96.36 PSNR:  8.45 MAXDIFF:  233 bytes:  7603200/  7603200
+dce624117fcd2b16f38e0a0a62b13fa7 *tests/data/fate/vsynth_lena-bpp1.out.rawvideo
+stddev:   83.18 PSNR:  9.73 MAXDIFF:  217 bytes:  7603200/  7603200