Makefile: DEBUG -> JL_DEBUG_BUILD to avoid LLVM conflict
Add code_native support for MCJIT
Add partial support for line info.

Use ';' as separator in LLVM function name, and add jl_demangle
MCJIT code_native fixes

Support LLVM trunk
Full backtrace line info
Fix disassembly line numbers
Properly initialize some variables.
Clean up merge cruft and make ';' mangling MCJIT-only
Use FunctionNameKind::ShortName, thanks to upstream making this available
Merge pull request #6737 from ihnorton/mcjit_disasm

MCJIT code_native support