Expose 'moduleToPkgConfAll' from 'PackageState'

Summary:
Having direct access to this field is going to enable Haddock to
compute in batch which modules to load before looking up instances
of external packages.

Reviewers: bgamari, monoidal

Reviewed By: monoidal

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5100

compiler/main/Packages.hs

@@ -7,7 +7,7 @@ module Packages (
         module PackageConfig,
 
         -- * Reading the package config, and processing cmdline args
-        PackageState(preloadPackages, explicitPackages, requirementContext),
+        PackageState(preloadPackages, explicitPackages, moduleToPkgConfAll, requirementContext),
         PackageConfigMap,
         emptyPackageState,
         initPackages,