ffplay: resize of the sdl window when -showmode 1/2 is used

[ami_stuff]

When I run ffplay (-showmode 1 or 2) with file which have audio and video stream then at the beginning sdl window will be resized from 640x480 to the real resolution of the video.

Maybe it would be possible to avoid this unnecessary resize and open sdl window with the size of the video.

C:\>ffplay -showmode 1 acelp16k.avi
ffplay version N-51106-g17c1881 Copyright (c) 2003-2013 the FFmpeg developers
  built on Mar 19 2013 13:49:37 with gcc 4.7.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libg
sm --enable-libilbc --enable-libmp3lame --enable-libopencore-amrnb --enable-libo
pencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-li
bschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-lib
twolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enabl
e-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 19.101 / 52. 19.101
  libavcodec     55.  1.100 / 55.  1.100
  libavformat    55.  0.100 / 55.  0.100
  libavdevice    55.  0.100 / 55.  0.100
  libavfilter     3. 47.104 /  3. 47.104
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
    nan A-V:  0.000 fd[avi @ 026a49c0] non-interleaved AVI
=   0 aq=    0KB vInput #0, avi, from 'acelp16k.avi':
, bitrate: 1445 kb/sB sq=    000:00:05.96, start: 0.000000B f=0/0
    Stream #0:0: Video: cinepak (cvid / 0x64697663), rgb24, 192x128, 24 tbr, 24
tbn, 24 tbc
    Stream #0:1: Audio: sipr (0[1][0][0] / 0x0130), 16000 Hz, mono, flt, 16 kb/s

   1.66 A-V: -0.004 fd=   1 aq=    1KB vq=   37KB sq=    0B f=0/0

[Carl Eugen Hoyos]

Fixed by Marton Balint in ad01fae8