configure: add missing avx2 support check

AVX2 support was introduced in Yasm 1.2.0, and some distros
like Debian still feature version 1.1.0
Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -4282,6 +4282,7 @@ EOF
         check_yasm "movbe ecx, [5]" && enable yasm ||
             die "yasm/nasm not found or too old. Use --disable-yasm for a crippled build."
         check_yasm "vextractf128 xmm0, ymm0, 0"      || disable avx_external avresample
+        check_yasm "vextracti128 xmm0, ymm0, 0"      || disable avx2_external
         check_yasm "vpmacsdd xmm0, xmm1, xmm2, xmm3" || disable xop_external
         check_yasm "vfmadd132ps ymm0, ymm1, ymm2"    || disable fma3_external
         check_yasm "vfmaddps ymm0, ymm1, ymm2, ymm3" || disable fma4_external