Fix wrong include in debugutil.cpp

Commit 8398f6990b added
    #include "debugutil.moc"
but debugutil.cpp doesn't contain anything that would produce such a
file.  This leads to a flood of AutoMoc warnings when building the QML
debugger test.

Presumably, it was meant to include moc_debugutil_p.cpp, so let's do
that.

Change-Id: I86dfe935e7a01388f6737124d9383ad53a772897
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

tests/auto/qml/debugger/shared/debugutil.cpp

@@ -260,4 +260,4 @@ QString debugJsServerPath(const QString &selfPath)
             + "/" + debugserver;
 }
 
-#include "debugutil.moc"
+#include <moc_debugutil_p.cpp>