fixup build error.

Author: matu3ba

lib/std/child_process.zig

@@ -1375,7 +1375,7 @@ fn windowsCreateProcess(app_name: [*:0]u16, cmd_line: [*:0]u16, envp_ptr: ?[*]u1
         null,
         null,
         windows.TRUE,
-        windows.PROCESS_CREATION_FLAGS.CREATE_UNICODE_ENVIRONMENT,
+        @enumToInt(windows.PROCESS_CREATION_FLAGS.CREATE_UNICODE_ENVIRONMENT),
         @ptrCast(?*anyopaque, envp_ptr),
         cwd_ptr,
         lpStartupInfo,