src/framing.c: close compile warning under windows whith msbuild
src/framing.c: close compile warning under windows whith msbuild

Close the C4244 warning while compiling under windows with cmake+msbuild.

Signed-off-by: Tristan Matthews <772c34063d5306b4ae4fb341f25f027152019fbd@videolan.org>

ShiftMediaProject/ogg,xiph/ogg,xiph/ogg,ShiftMediaProject/ogg