REALLY fix corePrepPgm type error. Actually tested this time.
Patch haste-pkg for GHC 7.4.
Use -package-conf instead of -package-db with GHC 7.4.
Use --package-conf instead of --package-db with GHC 7.4 in haste-boot.
Fix up haste-copy-pkg for GHC 7.4.
Make base build with GHC 7.4.
Fix Exception test case for GHC 7.4.