This patch unifies the implementation of the Bilateral Blur node across
CPU and GPU. The difference is due to two things. First, the CPU code
had a bug where the upper limit of the blur window was not included in
the accumulation. Second, CPU ignored pixels outside of the image while
GPU clamped them to the nearest boundary pixel. The latter difference
was aligned with GPU until we eventually add an option to control
boundary handing.
A few utilities were added to the node operation and memory buffer
classes to do clamped pixel reading.
Pull Request: https://projects.blender.org/blender/blender/pulls/117751
3d7e84f57d