Fix reload inheritance of post-modified addresses.

[Ian Bolton]

Hi Richard,

> This patch fixes a miscompilation of SPEC2006 gromacs with ARM+VFP.
> Thanks to Dave Gilbert for narrowing down the failure to a particular
> rtl instruction and a particular group of flags.

Your patch also fixes this:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47166

Thanks to Bernd for debugging this.

This patch is needed on trunk and 4.5 branch, so I hope it can be
reviewed soon.

Cheers,
Ian