Fix a typo.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@207339 138bc75d-0d04-0410-961f-82ee72b054a4
2014-01-31  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* doc/extend.texi (Vector Extensions): Document ?: in C++.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@207340 138bc75d-0d04-0410-961f-82ee72b054a4