Implement ffplay -L.

Patch by: Stefano Sabatini, stefano.sabatini-lala poste it

Originally committed as revision 13235 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/ffplay-doc.texi

@@ -33,6 +33,8 @@ ffplay [options] @file{input_file}
 show help
 @item -version
 show version
+@item -L
+show license
 @item -x @var{width}
 force displayed width
 @item -y @var{height}

ffplay.c

@@ -2435,6 +2435,7 @@ static int opt_thread_count(const char *opt, const char *arg)
 static const OptionDef options[] = {
     { "h", OPT_EXIT, {(void*)show_help}, "show help" },
     { "version", OPT_EXIT, {(void*)show_version}, "show version" },
+    { "L", OPT_EXIT, {(void*)show_license}, "show license" },
     { "x", HAS_ARG | OPT_FUNC2, {(void*)opt_width}, "force displayed width", "width" },
     { "y", HAS_ARG | OPT_FUNC2, {(void*)opt_height}, "force displayed height", "height" },
     { "s", HAS_ARG | OPT_VIDEO, {(void*)opt_frame_size}, "set frame size (WxH or abbreviation)", "size" },