Convert macros from plain QByteArray to a vector of structs

The old code model expected the macros as C++ formatted text
("#define Foo 42) but newer targets like the Clang codemodel expect key
value arguments like "-DFoo=42". So instead of parsing the text again and
again we use an abstract data description.

Task-number: QTCREATORBUG-17915
Change-Id: I0179fd13c48a581e91ee79bba9d42d501c26f19f
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/autotest/qtest/qttestparser.cpp

@@ -86,7 +86,7 @@ static bool qtTestLibDefined(const QString &fileName)
     const QList<CppTools::ProjectPart::Ptr> parts =
             CppTools::CppModelManager::instance()->projectPart(fileName);
     if (parts.size() > 0)
-        return parts.at(0)->projectDefines.contains("#define QT_TESTLIB_LIB");
+        return parts.at(0)->projectMacros.contains({"QT_TESTLIB_LIB"});
     return false;
 }