patch: fix compiler warning in includes/Rts.h

[Simon Marlow]

On 22/07/2009 21:16, Krister Walfridsson wrote:
> NetBSD defines _REENTRANT in its header files, so compiling ghc gives
> redefinition warnings for all files that are including includes/Rts.h.
>
> Fixed with the attached patch.

Thanks, will push.

Simon