Make ShadingSystemImpl::Shader() create a valid (even if empty) m_curattrib, even if Shader() takes an early out because no valid shader with that name could be found. See trac#74  http://reviewboard/r/668/
Make ShadingSystemImpl::Shader() create a valid (even if empty)
m_curattrib, even if Shader() takes an early out because no valid shader
with that name could be found.
See trac#74  http://reviewboard/r/668/


git-svn-id: 93cebb81a0f5cc00f31a7ad40d16024532691b70@416 a3683778-fedd-11de-87c3-653bb6514e15

Anteru/OpenShadingLanguage,imageworks/OpenShadingLanguage,mcanthony/OpenShadingLanguage,Anteru/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,rlmh/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,brechtvl/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,brechtvl/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,juvenal/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,juvenal/OpenShadingLanguage,svenstaro/OpenShadingLanguage,gzorin/OpenShadingLanguage,juvenal/OpenShadingLanguage,mcanthony/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,lgritz/OpenShadingLanguage,imageworks/OpenShadingLanguage,brechtvl/OpenShadingLanguage,gzorin/OpenShadingLanguage,gzorin/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,mcanthony/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,sjparker/OpenShadingLanguage,sjparker/OpenShadingLanguage,rlmh/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,juvenal/OpenShadingLanguage,brechtvl/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,rlmh/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,aconty/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,gzorin/OpenShadingLanguage,imageworks/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,sjparker/OpenShadingLanguage,rlmh/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,mcanthony/OpenShadingLanguage,Anteru/OpenShadingLanguage,gzorin/OpenShadingLanguage,lgritz/OpenShadingLanguage,Anteru/OpenShadingLanguage,svenstaro/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,svenstaro/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,sjparker/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,svenstaro/OpenShadingLanguage