fix LLVM 3.4 build (bug #41061) * configure.ac: Call new functions OCTAVE_LLVM_RAW_FD_OSTREAM_API and OCTAVE_LLVM_LEGACY_PASSMANAGER_API, check for Verifier.h header file * m4/acinclude.m4 (OCTAVE_LLVM_RAW_FD_OSTREAM_API): New function to detect correct raw_fd_ostream API * m4/acinclude.m4 (OCTAVE_LLVM_LEGACY_PASSMANAGER_API): New function to detect legacy passmanager API * libinterp/corefcn/jit-util.h: Use legacy passmanager namespace if necessary * libinterp/corefcn/pt-jit.h (class tree_jit): Use legacy passmanager class if necessary * libinterp/corefcn/pt-jit.cc: Include appropriate header files * libinterp/corefcn/pt-jit.cc (tree_jit::initialize): Use legacy passmanager if necessary * libinterp/corefcn/pt-jit.cc (tree_jit::optimize): Use correct API * libinterp/corefcn/jit-typeinfo.cc: Include appropriate header file