OSL 1.11.9.0

Release 1.11.9 -- 1 Nov 2020 (compared to 1.11.8)

• Build properly against Cuda 11 and OptiX 7.1. #1232
• Windows compile fixes. #1263 #1285
• PugiXML build fixes on some systems. #1262
• Fix asymptomatic potential runtime optimizer bug where certain
  multi-component values were not correctly recognized as nonzero. #1266
• Fix false positive with "debug_uninit" where certain while loops might be
  flagged as using uninitialized values when in fact they were not. #1252
• Slightly optimize by not copying output params to layers that will not be
  used. #1253
• Internals: use the final keyword in certain internal classes where
  applicable. #1260
• Cuda/OptiX back end: Add __CUDADEVRT_INTERNAL__ define to bitcode
  generation, needed to avoid duplicate cudaMalloc symbols with CUDA9+ #1271
• Fix build break against recent OIIO master change where m_mutex field was
  removed from ImageInput. #1281