Squashed 'luajit/' changes from f371ed6..2be62dc

2be62dc Fix exception unwind struct declaration.
9247541 Fix OSX build issue.
dd910f0 Fix initial maxslot for down-recursive traces.
3db3cc1 Fix compiler warnings.
926686a Fix OSX build issue.
45c067d FFI: Fix cts->L for cdata unsinking in snapshot restore.
ef59e54 Bump copyright date to 2014.
6964a77 Fix ABC elimination.
b779f31 Fix MinGW build.
ca67c89 MIPS: Cosmetic fix for interpreter.
89e8d70 Fix compilation of string.byte(s, nil, n).
279673d Fix MinGW build.
0ded8e8 Fix call unroll checks in the presence of metamethod frames.
916f09d x64: Fix store to upvalue for lightuserdata values.

git-subtree-dir: luajit
git-subtree-split: 2be62dcfcdea2c60047335e613fe5bd0b85911c2
Merge commit '530cf342dc90697094b7b95108d8ce5bd8b75ec6'