namespace scoping is not handled properly in function and template parameters

[dkrupp]

structural equivalence currently does not take namespace into consideration, but it should.

file: a.cc
namespace x{
class a;
}
void f(x::a);

file: imported.cc
namespace y{
class a;
}
void f(y::a);

The error is that f(x::a) is said to be equivalent with f(y::a)
and the import fails.

There is such error in bitcoin.

[balazske]

There is a related pull request #629.

[dkrupp]

there is a suspected problem with astreader in ASTContext getCanonicalTemplateTemplateParmDecl(..)