Small build system refactoring; no functional changes
Rename hs-suffix-rules to hs-suffix-way-rules
Rename hs-suffix-rules-srcdir to hs-suffix-way-rules-srcdir
Split non-way-specific variables off from distdir-way-opts into distdir-opts

The hsc2hs, alex and happy options variables are now also
non-way-specific, as the files are shared between all ways.
Separate the non-way-specific hs-suffix rules

This means we don't define them multiple times
Build fixes following build system refactoring
Merge branch 'master' of darcs.haskell.org:/srv/darcs//ghc