qemu-arm does not reject vrintz on non-v8 cpu

Hello,

It seems that qemu-arm does not reject some v8-only instructions as it should, but executes them "correctly".

For instance, while compiling/running some of the GCC ARM instrinsics tests, we noticed that
vrintz should be rejected on cortex-a9 for instance, while it is executed as if the instruction was supported.

objdump says:
   1074c:       f3fa05a0        vrintz.f32      d16, d16
and qemu -d in_asm says:
0x0001074c:  f3fa05a0      vabal.u<illegal width 64>    q8, d26, d16

The problem is still present in qemu-2.6.0