nodes: properly restore blend and stencil glstates
nodes: properly restore blend and stencil glstates

Fixes an issue where the stencil mask was not properly restored causing
the next stencil clear to use a stencil mask of 0 preventing the clear call
to have any effect.

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl