Do this so we can set float statuses once per mtvscr, rather than once
per Altivec instruction.
Signed-off-by: NNathan Froyd <froydnj@codesourcery.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6508 c046a42c-6fe2-441c-8c8c-71466251a162