Core: Remove potential bad access writes in SoftwareRender.
Core: Remove potential bad access writes in SoftwareRender.

There's potential to still segfault when the triangle is completely
outside the render buffer.

njwilson23/StereoPipeline,njwilson23/StereoPipeline,ScottMcMichael/StereoPipeline,ScottMcMichael/StereoPipeline,oleg-alexandrov/StereoPipeline,DougFirErickson/StereoPipeline,NeoGeographyToolkit/StereoPipeline,DougFirErickson/StereoPipeline,aaronknister/StereoPipeline,njwilson23/StereoPipeline,njwilson23/StereoPipeline,ScottMcMichael/StereoPipeline,NeoGeographyToolkit/StereoPipeline,NeoGeographyToolkit/StereoPipeline,oleg-alexandrov/StereoPipeline,aaronknister/StereoPipeline,oleg-alexandrov/StereoPipeline,NeoGeographyToolkit/StereoPipeline,njwilson23/StereoPipeline,ScottMcMichael/StereoPipeline,ScottMcMichael/StereoPipeline,DougFirErickson/StereoPipeline,aaronknister/StereoPipeline,DougFirErickson/StereoPipeline,aaronknister/StereoPipeline,DougFirErickson/StereoPipeline,NeoGeographyToolkit/StereoPipeline,NeoGeographyToolkit/StereoPipeline,DougFirErickson/StereoPipeline,ScottMcMichael/StereoPipeline,oleg-alexandrov/StereoPipeline,njwilson23/StereoPipeline,oleg-alexandrov/StereoPipeline,aaronknister/StereoPipeline,oleg-alexandrov/StereoPipeline