* include/ext/pb_ds/detail/binomial_heap_base_/debug_fn_imps.hpp
	(assert_node_consistent): Avoid ambiguous else warning.

	* include/ext/pb_ds/detail/debug_map_base.hpp: Include <iostream>.

	* include/bits/c++config: In debug-mode (and parallel-mode) set
	_GLIBCXX_EXTERN_TEMPLATE to -1, not 0, thus disabling extern
	templates only for basic_string (per libstdc++/21674).
	* include/bits/basic_string.tcc: Use extern templates when
	_GLIBCXX_EXTERN_TEMPLATE > 0.

From-SVN: r137990