Bump version namespace.

Bump version namespace.

2017-05-10  François Dumont  <fdumont@gcc.gnu.org>

	Bump version namespace.
	* config/abi/pre/gnu-versioned-namespace.ver: Bump version namespace
	from __7 to __8. Bump GLIBCXX_7.0 to GLIBCXX_8.0.
	* acinclude.m4 (libtool_VERSION): Bump to 8:0:0.
	* include/bits/c++config: Adapt.
	* include/bits/regex.h: Adapt.
	* include/experimental/bits/fs_fwd.h: Adapt.
	* include/experimental/bits/lfts_config.h: Adapt.
	* include/std/variant: Adapt.
	* python/libstdcxx/v6/printers.py: Adapt.
	* testsuite/libstdc++-prettyprinters/48362.cc: Adapt.
	* include/bits/stl_tree.h (_Rb_tree_impl<>): Remove _Is_pod_comparator
	template parameter when version namespace is active.

From-SVN: r247858