Add stage 06: Lua bootstrap

The goal of stage 06 is to try parse zig synax in lua. I pulled in
lpeglable 1.2.0 and parser-gen off github to get started. All of this
needs to be cleaned up rather soon.

Lua boostraps using tcc and musl from the previous stage. Since musl
0.6.0 doesn't support dynamic linking this build of lua doesn't support
shared libraries. I couldn't easily patch musl with dlopen and friends
so instead I link statically and call deps with c api.

06/parser-gen/parsers/lua-5.3.4-tests/locals.lua

@@ -0,0 +1,162 @@
+-- $Id: locals.lua,v 1.37 2016/11/07 13:11:28 roberto Exp $
+-- See Copyright Notice in file all.lua
+
+print('testing local variables and environments')
+
+local debug = require"debug"
+
+
+-- bug in 5.1:
+
+local function f(x) x = nil; return x end
+assert(f(10) == nil)
+
+local function f() local x; return x end
+assert(f(10) == nil)
+
+local function f(x) x = nil; local y; return x, y end
+assert(f(10) == nil and select(2, f(20)) == nil)
+
+do
+  local i = 10
+  do local i = 100; assert(i==100) end
+  do local i = 1000; assert(i==1000) end
+  assert(i == 10)
+  if i ~= 10 then
+    local i = 20
+  else
+    local i = 30
+    assert(i == 30)
+  end
+end
+
+
+
+f = nil
+
+local f
+x = 1
+
+a = nil
+load('local a = {}')()
+assert(a == nil)
+
+function f (a)
+  local _1, _2, _3, _4, _5
+  local _6, _7, _8, _9, _10
+  local x = 3
+  local b = a
+  local c,d = a,b
+  if (d == b) then
+    local x = 'q'
+    x = b
+    assert(x == 2)
+  else
+    assert(nil)
+  end
+  assert(x == 3)
+  local f = 10
+end
+
+local b=10
+local a; repeat local b; a,b=1,2; assert(a+1==b); until a+b==3
+
+
+assert(x == 1)
+
+f(2)
+assert(type(f) == 'function')
+
+
+local function getenv (f)
+  local a,b = debug.getupvalue(f, 1)
+  assert(a == '_ENV')
+  return b
+end
+
+-- test for global table of loaded chunks
+assert(getenv(load"a=3") == _G)
+local c = {}; local f = load("a = 3", nil, nil, c)
+assert(getenv(f) == c)
+assert(c.a == nil)
+f()
+assert(c.a == 3)
+
+-- old test for limits for special instructions (now just a generic test)
+do
+  local i = 2
+  local p = 4    -- p == 2^i
+  repeat
+    for j=-3,3 do
+      assert(load(string.format([[local a=%s;
+                                        a=a+%s;
+                                        assert(a ==2^%s)]], j, p-j, i), '')) ()
+      assert(load(string.format([[local a=%s;
+                                        a=a-%s;
+                                        assert(a==-2^%s)]], -j, p-j, i), '')) ()
+      assert(load(string.format([[local a,b=0,%s;
+                                        a=b-%s;
+                                        assert(a==-2^%s)]], -j, p-j, i), '')) ()
+    end
+    p = 2 * p;  i = i + 1
+  until p <= 0
+end
+
+print'+'
+
+
+if rawget(_G, "querytab") then
+  -- testing clearing of dead elements from tables
+  collectgarbage("stop")   -- stop GC
+  local a = {[{}] = 4, [3] = 0, alo = 1, 
+             a1234567890123456789012345678901234567890 = 10}
+
+  local t = querytab(a)
+
+  for k,_ in pairs(a) do a[k] = nil end
+  collectgarbage()   -- restore GC and collect dead fiels in `a'
+  for i=0,t-1 do
+    local k = querytab(a, i)
+    assert(k == nil or type(k) == 'number' or k == 'alo')
+  end
+end
+
+
+-- testing lexical environments
+
+assert(_ENV == _G)
+
+do
+local dummy
+local _ENV = (function (...) return ... end)(_G, dummy)   -- {
+
+do local _ENV = {assert=assert}; assert(true) end
+mt = {_G = _G}
+local foo,x
+A = false    -- "declare" A
+do local _ENV = mt
+  function foo (x)
+    A = x
+    do local _ENV =  _G; A = 1000 end
+    return function (x) return A .. x end
+  end
+end
+assert(getenv(foo) == mt)
+x = foo('hi'); assert(mt.A == 'hi' and A == 1000)
+assert(x('*') == mt.A .. '*')
+
+do local _ENV = {assert=assert, A=10};
+  do local _ENV = {assert=assert, A=20};
+    assert(A==20);x=A
+  end
+  assert(A==10 and x==20)
+end
+assert(x==20)
+
+
+print('OK')
+
+return 5,f
+
+end   -- }
+