Code review comment for lp:~ams-codesourcery/gcc-linaro/android

For the record, I'm not sure about the three-way Negative() entries
in linux.opt (mbionic = !mglibc, mglibc = !muclibc, muclibc = !mbionic).
Now we have three options, it isn't correct to say that one is the
negative of one of the others.

I'm also not sure that it's a good idea to remove the "-mglibc -muclibc"
%es from rs6000/linux64.h without anything to replace it.

Both are directly backported from the patch that was accepted upstream though,
and I don't think either of them is going to affect us or Ubuntu.