Revert "Add comments explaining #8754"

This reverts commit b626c3d4.

(cherry picked from commit 642bba34)

ghc/Main.hs

@@ -77,7 +77,7 @@ import Data.Maybe
 
 main :: IO ()
 main = do
-   defaultsHook -- See Note [-Bsymbolic and hooks]
+   defaultsHook
    hSetBuffering stdout LineBuffering
    hSetBuffering stderr LineBuffering
    GHC.defaultErrorHandler defaultFatalMessager defaultFlushOut $ do
@@ -821,23 +821,4 @@ unknownFlagsErr fs = throwGhcException $ UsageError $ concatMap oneError fs
             [] -> ""
             suggs -> "did you mean one of:\n" ++ unlines (map ("  " ++) suggs)) 
 
-{- Note [-Bsymbolic and hooks]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--Bsymbolic is a flag that prevents the binding of references to global
-symbols to symbols outside the shared library being compiled (see `man
-ld`). When dynamically linking, we don't use -Bsymbolic on the RTS
-package: that is because we want hooks to be overridden by the user,
-we don't want to constrain them to the RTS package.
-
-Unfortunately this seems to have broken somehow on OS X: as a result,
-defaultHooks (in hschooks.c) is not called, which does not initialize
-the GC stats. As a result, this breaks things like `:set +s` in GHCi
-(#8754). As a hacky workaround, we instead call 'defaultHooks'
-directly to initalize the flags in the RTS.
-
-A biproduct of this, I believe, is that hooks are likely broken on OS
-X when dynamically linking. But this probably doesn't affect most
-people since we're linking GHC dynamically, but most things themselves
-link statically.
--}
 foreign import ccall safe "defaultsHook" defaultsHook :: IO ()