mesa: Fix double-lock of Shared->FrameBuffers and usage of wrong mutex

Fixes: 7534c536
Fixes: 8cfb3e4e
Closes: mesa/mesa#3024
Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <mesa/mesa!5160>
56 jobs for master
latest