Made symbol searching plug-able through indexing support.

The indexing support for the built-in code model is moved to its own
file. Symbol searching will now call for a searcher through that support
interface, which will create a fully configured and ready-to-go searcher
that can be started in the/a future.

Change-Id: Idc3ee1c7c789a69fa05ee1d42415313dcea94cf8
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/cpptools/cppindexingsupport.cpp

@@ -36,4 +36,12 @@ CppIndexingSupport::~CppIndexingSupport()
 {
 }
 
+SymbolSearcher::SymbolSearcher(QObject *parent)
+    : QObject(parent)
+{
+}
+
+SymbolSearcher::~SymbolSearcher()
+{}
+
 } // namespace CppTools