Bug 456101 - class template is refering to itself in code completion

a CPPASTQualifiedName that represents some template instance can never
refer to a template of the same type

Change-Id: Iaf9a452e4797fc0e797e5ed5ccaadfb00ff4fb8f
Signed-off-by: Michi <woskimi@yahoo.de>
Reviewed-on: https://git.eclipse.org/r/38730
Reviewed-by: Sergey Prigogin <eclipse.sprigogin@gmail.com>
Tested-by: Sergey Prigogin <eclipse.sprigogin@gmail.com>