Cleaner reimplementation of _ENV 1/2

* Mimic semantics of 5.2
* Introduce ESETV, when specifically setting _ENV upvalue
* ESETV goes through list of upvalue users and sets GCfunc->env

This way we can have our cake (_ENV) and it eat too (compatible
with setfenv).

Signed-off-by: katlogic <git@git.git>
Cleaner reimplementation of _ENV 2/2

Signed-off-by: katlogic <git@git.git>
_ENV fixes

Signed-off-by: katlogic <git@git.git>
Match 5.2 debug.setupvalue(fn,1) more closely

Do equivalent of ESETV for lua_setupvalue, but
only if we identify the uv as actually being
global env.

Signed-off-by: katlogic <git@git.git>
Don't clash on system with existing luajit

Signed-off-by: katlogic <git@git.git>
Testing tag bump
Tag bump

Signed-off-by: katlogic <git@git.git>
UCLO JIT

* Checks that there are no upvalues to be closed in given trace
* Eliminate UCLO completely if that is the case

This assumes that upvalues state is consistent across each trace

(empirical results indicate that this is indeed the case,
but there might be some ugly corner cases).

This results in rather dramatic speedup of closure-heavy code
(see tests/clobench.lua). Next up: FNEW

Signed-off-by: katlogic <git@git.git>
Merge branch 'v2.1' of http://luajit.org/git/luajit-2.0
UCLO fixes

* rbase is in RA, not RD
* shrink slots only if not aborting the trace

Signed-off-by: katlogic <git@git.git>
Preliminary FNEW JIT

Signed-off-by: katlogic <git@git.git>
on/off FNEW lifting

Signed-off-by: katlogic <git@git.git>
Merge branch 'v2.1' of http://luajit.org/git/luajit-2.0
Display upvalues in BC disassembly

Signed-off-by: katlogic <git@git.git>
FENV/llift opT

Signed-off-by: katlogic <git@git.git>
More accurate closure lifting

Passes most of the tests now

TBD: xpcall in coroutine.wrap when top-level closure is lifted

Signed-off-by: katlogic <git@git.git>
Merge branch 'v2.1' of http://luajit.org/git/luajit-2.0
5.2 compat patterns

Signed-off-by: katlogic <git@git.git>
more PM tests

Signed-off-by: katlogic <git@git.git>
KT and string tests

Signed-off-by: katlogic <git@git.git>