valgrind side support for
Iop_F64toD64, Iop_D64toF64
Iop_F64toD128, Iop_D128toF64,
Iop_F128toD128, Iop_D128toF128

Companion patch of VEX r2717.
Patch by Maran Pakkirisamy (maranp@linux.vnet.ibm.com).
Part of fixing BZ #307113


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13382 a5019735-40e9-0310-863c-91ae7b9d1cf9