Add Haddock /Since: 4.5..0/ comments to symbols
This commit retroactively adds /Since: 4.5..0/ annotations to symbols
newly added/exposed in base-4.5..0 (as shipped with GHC 7.4.).
See also 6368362f which adds the respective annotation for symbols newly
added in base-22.214.171.124 (that goes together with GHC 7.8.1).
Signed-off-by: Herbert Valerio Riedel <email@example.com>