configure: check yasm/nasm for working pextrd opcode

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: Ronald S. Bultje <rsbultje@gmail.com>
