NASM versions older than 2.08 fail to build ffmpeg with several
"error: operation size not specified" errors but this is not caught in
configure.

Fix that by checking if "pextrd [eax], xmm0, 1" works in configure.
Signed-off-by: NRonald S. Bultje <rsbultje@gmail.com>
(cherry picked from commit 48545a8f)