add opam exec -- to Windows build tasks

.vscode/tasks.json

@@ -9,7 +9,7 @@
 				"command": "eval $(opam env) && make ADD_REVISION=1 -s -j haxe",
 			},
 			"windows": {
-				"command": "make ADD_REVISION=1 -f Makefile.win -s -j haxe"
+				"command": "opam exec -- make ADD_REVISION=1 -f Makefile.win -s -j haxe"
 			},
 			"problemMatcher": [],
 			"group": {
@@ -22,7 +22,7 @@
 			"type": "shell",
 			"command": "make -s -j libs",
 			"windows": {
-				"command": "make -f Makefile.win -s -j libs"
+				"command": "opam exec -- make -f Makefile.win -s -j libs"
 			},
 			"problemMatcher": []
 		},
@@ -31,7 +31,7 @@
 			"type": "shell",
 			"command": "make -s haxelib",
 			"windows": {
-				"command": "make -f Makefile.win -s haxelib"
+				"command": "opam exec -- make -f Makefile.win -s haxelib"
 			},
 			"problemMatcher": ["$haxe", "$haxe-absolute"]
 		},
@@ -40,7 +40,7 @@
 			"type": "shell",
 			"command": "make s -j libs && make ADD_REVISION=1 -s -j haxe && make -s haxelib",
 			"windows": {
-				"command": "make -f Makefile.win -s -j libs && make ADD_REVISION=1 -f Makefile.win -s -j haxe && make -f Makefile.win -s haxelib"
+				"command": "opam exec -- make -f Makefile.win -s -j libs && make ADD_REVISION=1 -f Makefile.win -s -j haxe && make -f Makefile.win -s haxelib"
 			},
 			"problemMatcher": ["$haxe", "$haxe-absolute"]
 		},