Bump libdrm dependency to 2.4.86

In 94e4068b, the libdrm dependency was bumped to 2.4.83, which enabled us to remove a bunch of error-prone ifdefs by making atomic and modifier support mandatory.

We determined in the discussion of !311 (merged) that it was safe to push the dependency as high as 2.4.91, as that was what was available in major distributions.

Bumping to 2.4.86 allows us to remove one more ifdef, from aspect-ratio support, as that was added in mesa/drm@0d889201.

Signed-off-by: Daniel Stone daniels@collabora.com

/cc @leandrohrb @pq @evelikov