patch 8.1.1028: MS-Windows: memory leak when creating terminal fails

Problem:    MS-Windows: memory leak when creating terminal fails.
Solution:   Free the command. (Ken Takata, closes #4138)

src/os_win32.c

@@ -4866,7 +4866,10 @@ mch_call_shell_terminal(
     argvar[1].v_type = VAR_UNKNOWN;
     buf = term_start(argvar, NULL, &opt, TERM_START_SYSTEM);
     if (buf == NULL)
+    {
+	vim_free(newcmd);
 	return 255;
+    }
 
     job = term_getjob(buf->b_term);
     ++job->jv_refcount;

src/version.c

@@ -779,6 +779,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1028,
 /**/
     1027,
 /**/