libstdc++: Fix docs for --enable-vtable-verify [PR120698]

libstdc++-v3/ChangeLog:

	PR libstdc++/120698
	* doc/xml/manual/configure.xml: Do not claim that vtv is enabled
	by default.
	* doc/html/manual/configure.html: Regenerate.

(cherry picked from commit d199a9c7c5034d0eddb3380a58342a5bcbe6febd)
2 files changed