message: build: fix make clean on OSX
  Rebased-From:
  Rebased-By: Wladimir J. van der Laan
diff: @@ -168,4 +168,4 @@ CLEANFILES = $(OSX_DMG) $(BITCOIN_WIN_INSTALLER)
  .INTERMEDIATE: $(OSX_APP_BUILT) $(COVERAGE_INFO)
  clean-local:
  - rm -rf test_bitcoin.coverage/ total.coverage/
  + rm -rf test_bitcoin.coverage/ total.coverage/ $(OSX_APP)
  