mesa/formatquery: handle unmodified buffer for SAMPLES on the 64-bit query

mesa/formatquery: handle unmodified buffer for SAMPLES on the 64-bit query

From arb_internalformat_query2 spec:

" If <internalformat> is not color-renderable, depth-renderable, or
  stencil-renderable (as defined in section 4.4.4), or if <target>
  does not support multiple samples (ie other than
  TEXTURE_2D_MULTISAMPLE, TEXTURE_2D_MULTISAMPLE_ARRAY, or
  RENDERBUFFER), <params> is not modified."

So there are cases where the buffer should not be modified. As the
64-bit query is a wrapper over the 32-bit query, we can't just copy
the values to the equivalent 32-bit buffer, as that would fail if the
original params contained values greater that INT_MAX. So we need to
copy-back only the values that got modified by the 32-bit query. We do
that by filling the temporal buffer by negatives, as the 32-bit query
should not return negative values ever.

Reviewed-by: Dave Airlie <airlied@redhat.com>