Remove the user package db from GHC_PACKAGE_PATH
Remove the user package db from GHC_PACKAGE_PATH

The user and global package DBs are removed from the GHC_PACKAGE_PATH by
virtue of GHC_PACKAGE_PATH no longer ending in a `:`. A reasonable guess as to
the location of the global database is added to the GHC_PACKAGE_PATH.

The global package DB path is probably wrong for custom installations and for
Windows machines.

headprogrammingczar/cabal,kosmikus/cabal,seereason/cabal,Peaker/cabal,plumlife/cabal,sopvop/cabal,mmakowski/cabal,triplepointfive/cabal,rimmington/cabal,mmakowski/cabal,garetxe/cabal,eric-stanley/cabal,typelead/epm,ian-ross/cabal,kosmikus/cabal,typelead/epm,lukexi/cabal,kolmodin/cabal,enolan/cabal,edsko/cabal,plumlife/cabal,Helkafen/cabal,x-y-z/cabal,bennofs/cabal,Heather/cabal,ian-ross/cabal,Peaker/cabal,headprogrammingczar/cabal,randen/cabal,gbaz/cabal,ghc-android/cabal,christiaanb/cabal,thomie/cabal,valderman/cabal,corngood/cabal,martinvlk/cabal,garetxe/cabal,plow-technologies/cabal,trskop/cabal,corngood/cabal,themoritz/cabal,mydaum/cabal,thoughtpolice/cabal,gridaphobe/cabal,anton-dessiatov/cabal,fugyk/cabal,themoritz/cabal,randen/cabal,mydaum/cabal,enolan/cabal,anton-dessiatov/cabal,lukexi/cabal,edsko/cabal,x-y-z/cabal,plow-technologies/cabal,beni55/cabal,ghc-android/cabal,eric-stanley/cabal,Heather/cabal,gbaz/cabal,trskop/cabal,thoughtpolice/cabal,triplepointfive/cabal,christiaanb/cabal,kolmodin/cabal,thomie/cabal,bennofs/cabal,martinvlk/cabal,Helkafen/cabal,gridaphobe/cabal,sopvop/cabal,rimmington/cabal,fugyk/cabal,seereason/cabal,mightybyte/cabal,beni55/cabal,valderman/cabal,mightybyte/cabal,sopvop/cabal,themoritz/cabal