[commit: ghc] master's head updated: Fix #16391 by using occCheckExpand in TcValidity (068b7e9)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

Branch 'master' now includes:

     4ca271d testsuite: Introduce fragile modifier
     910185a testsuite: Mark heapprof001 as fragile on i386
     a65bcbe testsuite: Use fragile modifier for more tests
     f624dc1 gitlab-ci: Don't allow i386-deb9 to fail
     07f378c Add tests for Trac #16221 and #16342
     25c3dd3 Test Trac #16263
     7a68254 Fix #16392: revertCAFs in external interpreter when necessary
     068b7e9 Fix #16391 by using occCheckExpand in TcValidity