Debugger: Don't check for existence of gdb.inferior.threads()

All supported versions have it in that context.

Change-Id: Iafff4760ba521ffc9abc4e05dbbc9263ed6fe21a
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
C++: add semantic support for C++11 alias decls.

Task-number: QTCREATORBUG-9386

Change-Id: Ia68f3866c122ca5261dd73b2c740b47fb15744fc
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>