• Belatedly update `graphics/appleseed' to version 1.6.0, the latest version where OSL support is optional (further updates require RTTI enabled in both LLVM and OSL, and thus currently not possible)
• Allow to build in C++11 mode and backport a patch to fix spinlock initialization to match the way it is initialized internally by Boost: copy and assignment operators are deleted, which this logic was attempting to use (in fact, it's surprising that it was working before because it was most likely not possible even with C++98, unless this is a very recent change in Boost) [*]
• While here, adjust OSL_BROKEN message to give the specific reason

PR: 222392 [*]
Submitted by: Roger Leigh