Which RTS does ghci use?

[Ben Lippmeier]

I'm trying to fix http://hackage.haskell.org/trac/ghc/ticket/1015 (segv 
on solaris with regex-posix). This bug only appears when using ghci. I 
think it's something to do with weak pointers / finalizers, but my hacks 
on the rts seem to not affect the stage2 compiler.

ie:

ghc$ cd rts
ghc/rts$ ... hack on rts ...
ghc/rts$ cd ../compiler
ghc/compiler$ make stage=2
ghc/compiler$ ../ghc/stage2-inplace/ghc --interactive       
              -- no effect??

If I, say, modify rts/Weak.c:scheduleFinalizers to print out what 
finalizes are being run on each call, how do I make ghci with the stage2 
compiler use this change?

Thanks,
Ben.