Suppress missing haddock warning for some packages.

Allow a hardcoded whitelist of packages (currently 'rts') to not have
haddocks. When building several packages together, the accumulation of
these spurious warnings can make it a bit harder to notice legitimate
errors.
Rename a lamda var to avoid shadow warning.
Merge pull request #1231 from kowey/kowey

suppress annoying missing haddock warning for whitelist (rts)