Bot http://green.lab.llvm.org/green/job/clang-stage2-Rthinlto/ fails
with an error
error: 'llvm/IR/Attributes.inc' file not found
while building OrcError. It happens because OrcError.cpp depends on
'LLVM_ExecutionEngine' module through including
"llvm/ExecutionEngine/Orc/OrcError.h". And `LLVM_ExecutionEngine'
depends on 'LLVM_intrinsic_gen' through ExecutionEngine.h including
"llvm/IR/Module.h". But we fail to build 'LLVM_intrinsic_gen' because
'llvm/IR/Attributes.inc' is missing. Note that this problem doesn't
happen in a non-modular build because OrcError files don't try to
include .inc files transitively.
Fix by making the target LLVMOrcError depend on intrinsics_gen the same
way LLVMOrcJIT does.