Prevent gnome-shell f/ showing 'unresponsive app' during debug

LibreOffice advertises NET_WM_PING atom, so mutter rightfully
warns of an unresponsive application during debugging.

Hack that out unconditionally for dbg_util builds, as per
https://bugzilla.redhat.com/show_bug.cgi?id=981149 upstream refuses
to make this configurable in any way.

Change-Id: I12edbb49a067ad20903ca9b62557ee02c90c8a6e
Reviewed-on: https://gerrit.libreoffice.org/43618Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

vcl/unx/generic/window/salframe.cxx

@@ -689,8 +689,12 @@ void X11SalFrame::Init( SalFrameStyleFlags nSalFrameStyle, SalX11Screen nXScreen
         Atom a[3];
         int  n = 0;
         a[n++] = pDisplay_->getWMAdaptor()->getAtom( WMAdaptor::WM_DELETE_WINDOW );
+
+#ifndef DBG_UTIL
         if( pDisplay_->getWMAdaptor()->getAtom( WMAdaptor::NET_WM_PING ) )
             a[n++] = pDisplay_->getWMAdaptor()->getAtom( WMAdaptor::NET_WM_PING );
+#endif
+
         if( (nSalFrameStyle & SalFrameStyleFlags::OWNERDRAWDECORATION) )
             a[n++] = pDisplay_->getWMAdaptor()->getAtom( WMAdaptor::WM_TAKE_FOCUS );
         XSetWMProtocols( GetXDisplay(), GetShellWindow(), a, n );