testsuite: Print summary even if interrupted
testsuite: Print summary even if interrupted

Fixes #15265.

Reviewers: osa1

Reviewed By: osa1

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #15265

Differential Revision: https://phabricator.haskell.org/D4841

sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc