Add warning comment about Mach-O section name hack.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Trailing whitespaces
Restore old names of comparison primops

In 6579a6c we removed existing comparison primops and introduced new ones
returning Int# instead of Bool. This commit (and associated commits in
array, base, dph, ghc-prim, integer-gmp, integer-simple, primitive, testsuite and
template-haskell) restores old names of primops. This allows us to keep
our API cleaner at the price of not having backwards compatibility.