add ghc/docs/libraries to the documentation built for a GHC binary
distribution.
GhcMainDir = ghc
GhcBinDistDirs = ghc hslibs
GhcMainDir = ghc
GhcBinDistDirs = ghc hslibs
-GhcBinDistDocs = docs ghc/docs/users_guide
+GhcBinDistDocs = docs ghc/docs/users_guide ghc/docs/libraries
GhcBinDistPrlScripts = ghc stat2resid hstags mkdependHS
GhcBinDistLibPrlScripts = hscpp
GhcBinDistPrlScripts = ghc stat2resid hstags mkdependHS
GhcBinDistLibPrlScripts = hscpp