swrast: take ownership rather than adding reference for new renderbuffers

This avoids locking in the reference calls and fixes a leak after the
RefCount initialisation was change from 0 to 1.

Fixes: 32141e53d1520 (mesa: tidy up renderbuffer RefCount initialisation)

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
2 files changed