Removed compiler option LUA_COMPAT_LOOPVAR

It makes loop variables read-only, but it does not restore the old
semantics, so it is not helpful for compatibility.

lparser.c

@@ -1685,22 +1685,13 @@ static void forbody (LexState *ls, int base, int line, int nvars, int isgen) {
 }
 
 
-/*
-** Control whether for-loop control variables are read-only
-*/
-#if LUA_COMPAT_LOOPVAR
-#define LOOPVARKIND	VDKREG
-#else  /* by default, these variables are read only */
-#define LOOPVARKIND	RDKCONST
-#endif
-
 static void fornum (LexState *ls, TString *varname, int line) {
   /* fornum -> NAME = exp,exp[,exp] forbody */
   FuncState *fs = ls->fs;
   int base = fs->freereg;
   new_localvarliteral(ls, "(for state)");
   new_localvarliteral(ls, "(for state)");
-  new_varkind(ls, varname, LOOPVARKIND);  /* control variable */
+  new_varkind(ls, varname, RDKCONST);  /* control variable */
   checknext(ls, '=');
   exp1(ls);  /* initial value */
   checknext(ls, ',');
@@ -1727,7 +1718,7 @@ static void forlist (LexState *ls, TString *indexname) {
   new_localvarliteral(ls, "(for state)");  /* iterator function */
   new_localvarliteral(ls, "(for state)");  /* state */
   new_localvarliteral(ls, "(for state)");  /* closing var. (after swap) */
-  new_varkind(ls, indexname, LOOPVARKIND);  /* control variable */
+  new_varkind(ls, indexname, RDKCONST);  /* control variable */
   /* other declared variables */
   while (testnext(ls, ',')) {
     new_localvar(ls, str_checkname(ls));

luaconf.h

@@ -348,15 +348,6 @@
 #endif
 
 
-/*
-@@ LUA_COMPAT_LOOPVAR makes for-loop control variables not read-only,
-** as they were in previous versions.
-*/
-#if !defined(LUA_COMPAT_LOOPVAR)
-#define LUA_COMPAT_LOOPVAR	0
-#endif
-
-
 /*
 @@ LUA_COMPAT_MATHLIB controls the presence of several deprecated
 ** functions in the mathematical library.

manual/manual.of

@@ -9623,9 +9623,6 @@ makes @id{global} a regular word.
 The control variable in @Rw{for} loops is read only.
 If you need to change it,
 declare a local variable with the same name in the loop body.
-
-The compilation option @id{LUA_COMPAT_LOOPVAR} (see @id{luaconf.h})
-makes these variables regular (writable).
 }
 
 @item{