[PATCH] [PowerPC] [RFA] Fix PR target/53559 ICE on altivec builtins stv[l|r]x[l]

[Edmar]

I regression tested the patch presented in the PR:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53559

for the following branches:
4.5 branch svn revision 188125
4.6 branch svn revision 188124
4.7 branch svn revision 188128
4.8 trunk svn revision 187734

All bootstrapped with no regressions for powerpc64 target.

Thanks
Edmar