Hi,

Whilst working on the Reproducible Builds effort [0], we noticed that
mage could not be built reproducibly.

This is because the testsuite generates a mage_output_file.go file,
so that if the tests are skipped (ie. via nocheck), then the binary
package will differ.

Patch attached that removes this file after the testsuite is run.

 [0] https://reproducible-builds.org/


Regards,