ffmpeg: don't force Intel Core 2 optimizations if not building 64-bit on Solaris

Signed-off-by: Rafaël Carré <funman@videolan.org>
ffmpeg: explicitly set the target OS for Solaris

Signed-off-by: Rafaël Carré <funman@videolan.org>
ffmpeg: fix style concerns for Solaris section

Signed-off-by: Rafaël Carré <funman@videolan.org>