Small changes in the header of binary files

- LUAC_VERSION is equal to LUA_VERSION_NUM, and it is stored
as an int.

- 'sizeof(int)' and 'sizeof(size_t)' removed from the header, as
the binary format does not depend on these sizes. (It uses its
own serialization for unsigned integer values.)

testes/calls.lua

@@ -397,17 +397,15 @@ assert((function (a) return a end)() == nil)
 
 print("testing binary chunks")
 do
-  local header = string.pack("c4BBc6BBBBBj",
-    "\27Lua",                -- signature
-    5*16 + 4,                -- version 5.4
-    0,                       -- format
-    "\x19\x93\r\n\x1a\n",    -- data
-    string.packsize("i"),    -- sizeof(int)
-    string.packsize("T"),    -- sizeof(size_t)
-    4,                       -- size of instruction
-    string.packsize("j"),    -- sizeof(lua integer)
-    string.packsize("n"),    -- sizeof(lua number)
-    0x5678                   -- LUAC_INT
+  local header = string.pack("c4BBBc6BBBj",
+    "\27Lua",                                  -- signature
+    (504 >> 7) & 0x7f, (504 & 0x7f) | 0x80,    -- version 5.4 (504)
+    0,                                         -- format
+    "\x19\x93\r\n\x1a\n",                      -- data
+    4,                                         -- size of instruction
+    string.packsize("j"),                      -- sizeof(lua integer)
+    string.packsize("n"),                      -- sizeof(lua number)
+    0x5678                                     -- LUAC_INT
     -- LUAC_NUM may not have a unique binary representation (padding...)
   )
   local c = string.dump(function () local a = 1; local b = 3; return a+b*3 end)