Improve ULOAD forwarding for open upvalues.
Merge branch 'master' into v2.1
FFI: Add missing GC steps for callback argument conversions.
Merge branch 'master' into v2.1
DynASM/x86: Add lock prefix.
Add support for multilib distro builds.
Merge branch 'master' into v2.1
Fix compilation on NetBSD/x64.

Thanks to Justin Cormack.
Merge branch 'master' into v2.1
Fix compiler warning.
DynASM/x64: Add VREG support to mov64.

Thanks to Peter Cawley.
Merge branch 'master' into v2.1
Merge remote-tracking branch 'upstream/v2.1'