remove old mt leftovers (see https://github.com/HaxeFoundation/haxe/commit/09ce6695e09fdea461a5de2458d1980f554fe7c9#commitcomment-10262976)

main.ml

@@ -1396,7 +1396,6 @@ try
 	process_ref := process;
 	process ctx.com.args;
 	process_libs();
-	(try ignore(Common.find_file com "mt/Include.hx"); Common.raw_define com "mt"; with Not_found -> ());
 	if com.display <> DMNone then begin
 		com.warning <- message ctx;
 		com.error <- error ctx;

std/flash/Boot.hx

@@ -51,7 +51,6 @@ class Boot extends flash.display.MovieClip {
 	public static var skip_constructor = false;
 
 	function start() {
-		#if (mt && !doc_gen) mt.flash.Init.check(); #end
 		#if dontWaitStage
 			init();
 		#else

std/haxe/unit/TestCase.hx

@@ -24,7 +24,7 @@ import haxe.PosInfos;
 
 @:keepSub
 @:publicFields
-class TestCase #if mt_build implements mt.Protect #end {
+class TestCase {
 	public var currentTest : TestStatus;
 
 	public function new( ) {

std/js/_std/HxOverrides.hx

@@ -60,11 +60,7 @@ class HxOverrides {
 	}
 
 	static function cca( s : String, index : Int ) : Null<Int> {
-		#if mt
-		var x = (cast s).cca(index);
-		#else
 		var x = (cast s).charCodeAt(index);
-		#end
 		if( x != x ) // fast isNaN
 			return untyped undefined; // isNaN will still return true
 		return x;
@@ -138,10 +134,6 @@ class HxOverrides {
 		__feature__('HxOverrides.indexOf', if( Array.prototype.indexOf ) __js__("HxOverrides").indexOf = function(a,o,i) return Array.prototype.indexOf.call(a, o, i));
 		__feature__('HxOverrides.lastIndexOf', if( Array.prototype.lastIndexOf ) __js__("HxOverrides").lastIndexOf = function(a,o,i) return Array.prototype.lastIndexOf.call(a, o, i));
 #end
-
-#if mt
-		if( String.prototype.cca == null ) String.prototype.cca = String.prototype.charCodeAt;
-#end
 	}
 
 }