llvm BPF target: add missed source files
Otherwise, linking llvm binaries with this target enabled (which is not
the default) will fail with a number of undefined symbol errors:
ld: error: undefined symbol: llvm::initializeBPFAdjustOptPass(llvm::PassRegistry&) ld: error: undefined symbol: llvm::initializeBPFCheckAndAdjustIRPass(llvm::PassRegistry&) ld: error: undefined symbol: llvm::createBPFCheckAndAdjustIR() ld: error: undefined symbol: llvm::createBPFAdjustOpt() ld: error: undefined symbol: llvm::BPFAdjustOptPass::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&)
Reported by: Michael Dexter <editor@callfortesting.org>
MFC after: 3 days