detect C++ errors to fix 2288 and 18770
gcc/cp/
	PR c++/2288
	PR c++/18770
	* name-lookup.h (enum scope_kind): Add sk_cond.
	* name-lookup.c (pushdecl_maybe_friend): Get scope of shadowed local.
	Detect and report error for redeclaration from for-init or if
	or switch condition.
	(begin_scope): Handle sk_cond.
	* semantics.c (begin_if_stmt): Use sk_cond.
	(begin switch_stmt): Ditto.
gcc/testsuite/
	PR c++/2288
	PR c++/18770
	* g++.old-deja/g++.jason/cond.C: Remove xfails.
	* g++.dg/parse/pr18770.C: New test.
	* g++.dg/cpp0x/range-for5.C: Add dg-error marker.

Co-Authored-By: Nathan Froyd <froydnj@codesourcery.com>

From-SVN: r174307