llvm boostrap? Clang failures.

[Jeffrey Bouquet]

The "update clang" messages in UPDATING seem to not fix...
 ...llvm/include/llvm/ADT/StringRef.h: fatal error:
 'algorithm' file not found
make stopped in /usr/src/lib/clang/lib/libllvmsupport...
The entire build fails similarly,
also in any subtree I try to start from (clang, lib/clang... etc etc)

Previously, the system was upgraded from another successful installworld by rsync'ing the
/obj IIRC... 
Also I've tried parameters such as CPP=/usr/local/bin/clang-cpp36   to no avail...