Merge from trunk:

* Fix issue with const rvalue references in Boost.Variant (fixes #8988)
* Get rid of Boost.Variant hand written non-usable move emulation and use Boost.Move instead(refs #7601). This does not mean that Boost.Variant supports move emulation now, but removes duplicate/non-working code and makes sure that Boost.Variant is able to work with boost::move

[SVN r85408]

libs/variant

@@ -1 +1 @@
-Subproject commit 8507087c59523487be0f2bcbb529893ac00a6248
+Subproject commit 76f2c0fc19adebc1b56a325188b55e705c476f05