`make -f posix.mk clean` target appears broken

[mdegans]

 $ make -f posix.mk clean
make -C posix -f posix.mk clean
make[1]: Entering directory '/home/anzu/Projects/c-core/posix'
rm pubnub_advanced_history_sample pubnub_sync_sample pubnub_sync_subloop_sample cancel_subscribe_sync_sample pubnub_sync_publish_retry pubnub_publish_via_post_sample pubnub_callback_sample pubnub_callback_subloop_sample subscribe_publish_callback_sample pubnub_fntest pubnub_console_sync pubnub_console_callback pubnub_sync.a pubnub_callback.a subscribe_publish_from_callback publish_callback_subloop_sample publish_queue_callback_subloop *.o *.dSYM
rm: cannot remove '*.dSYM': No such file or directory
posix.mk:190: recipe for target 'clean' failed
make[1]: *** [clean] Error 1
make[1]: Leaving directory '/home/anzu/Projects/c-core/posix'
posix.mk:13: recipe for target 'clean' failed
make: *** [clean] Error 2

Fix is to put a hyphen before rm

Would you accept a PR resolving the issue this way?