Allow atomic update of NameCache in readHieFile

The situation arises in ghcide where multiple different threads may need to
update the name cache, therefore with the older interface it could happen
that you start reading a hie file with name cache A and produce name cache
A + B, but another thread in the meantime updated the namecache to A +
C. Therefore if you write the new namecache you will lose the A' updates
from the second thread.

Updates haddock submodule

1 files changed, 0 insertions, 0 deletions

diff --git a/utils/haddock b/utils/haddock
-Subproject c60995fe05d9cc267e892448604b8b96a705ccc
+Subproject 97f301a63ea8461074bfaa1486eb798e4be65f1