Update lua from 5.1.1 to 5.1.5

This keeps all the SM patches intact, but applies the 5.1.5 fixes on
top. All newlines normalized to make diffing with upstream easier.

https://www.lua.org/bugs.html#5.1.2
https://www.lua.org/bugs.html#5.1.3
https://www.lua.org/bugs.html#5.1.4
https://www.lua.org/bugs.html#5.1.5

extern/lua-5.1/etc/strict.lua

@@ -6,6 +6,8 @@
 -- anywhere or assigned to inside a function.
 --
 
+local getinfo, error, rawset, rawget = debug.getinfo, error, rawset, rawget
+
 local mt = getmetatable(_G)
 if mt == nil then
   mt = {}
@@ -14,9 +16,14 @@ end
 
 mt.__declared = {}
 
+local function what ()
+  local d = getinfo(3, "S")
+  return d and d.what or "C"
+end
+
 mt.__newindex = function (t, n, v)
   if not mt.__declared[n] then
-    local w = debug.getinfo(2, "S").what
+    local w = what()
     if w ~= "main" and w ~= "C" then
       error("assign to undeclared variable '"..n.."'", 2)
     end
@@ -26,7 +33,7 @@ mt.__newindex = function (t, n, v)
 end
   
 mt.__index = function (t, n)
-  if not mt.__declared[n] and debug.getinfo(2, "S").what ~= "C" then
+  if not mt.__declared[n] and what() ~= "C" then
     error("variable '"..n.."' is not declared", 2)
   end
   return rawget(t, n)