Fraser Tweedale authored Apr 10, 2019 and Marge Bot committed Apr 15, 2019

Directives in .ghci files in the current directory ("local .ghci")
can be overridden by global files.  Change the order in which the
configs are loaded: global and $HOME/.ghci first, then local.

Also introduce a new field to GHCiState to control whether local
.ghci gets sourced or ignored.  This commit does not add a way to
set this value (a subsequent commit will add this), but the .ghci
sourcing routine respects its value.

Fixes: ghc/ghc#14689
Related: ghc/ghc#6017
Related: ghc/ghc#14250