live: Fix MSVC hot code reloading (#2460)

vlib/compiler/live.v

@@ -29,6 +29,14 @@ fn (v &V) generate_hotcode_reloading_declarations() {
 	} else {
 		if v.pref.is_so {
 			cgen.genln('HANDLE live_fn_mutex;')
+			cgen.genln('
+void pthread_mutex_lock(HANDLE *m) {
+	WaitForSingleObject(*m, INFINITE);
+}
+
+void pthread_mutex_unlock(HANDLE *m) {
+	ReleaseMutex(*m);
+}')
 		}
 		if v.pref.is_live {
 			cgen.genln('HANDLE live_fn_mutex = 0;')

vlib/os/os.v

@@ -660,8 +660,10 @@ pub fn write_file(path, text string) {
 }
 
 pub fn clear() {
+	$if !windows {
 		C.printf('\x1b[2J')
 		C.printf('\x1b[H')
+	}
 }
 
 fn on_segfault(f voidptr) {