don't return junk from wxGetOsVersion() if we failed to execute 'uname -r' (thanks coverity)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45141 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/unix/utilsunx.cpp

@@ -915,9 +915,9 @@ wxOperatingSystemId wxGetOsVersion(int *verMaj, int *verMin)
     // get OS version
     int major, minor;
     wxString release = wxGetCommandOutput(wxT("uname -r"));
-    if ( !release.empty() && wxSscanf(release, wxT("%d.%d"), &major, &minor) != 2 )
+    if ( release.empty() || wxSscanf(release, wxT("%d.%d"), &major, &minor) != 2 )
     {
-        // unrecognized uname string format
+        // failed to get version string or unrecognized format
         major =
         minor = -1;
     }