Resolves: rhbz#1092589 Thoroughly check whether JRE is still present

...not only on Mac OS X.  Was able to reproduce this on Fedora 20 where current
JRE was /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.5.x86_64 but for whatever reason
there was also a left-behind /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.0.x86_64 tree
(containing just a handful of sub-dirs, but no real content) that was still
recorded in my ~/.config/libreoffice/4/user/config/javasettings_Linux_X86_64.xml

Change-Id: Ie477c5a506a430f6c29525f6c558dbc18bbf1c48
(cherry picked from commit f5ed2f4e926016d23617355c94dd2292b40e6986)
Reviewed-on: https://gerrit.libreoffice.org/9279
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/jvmfwk/plugins/sunmajor/pluginlib/sunjavaplugin.cxx b/jvmfwk/plugins/sunmajor/pluginlib/sunjavaplugin.cxx
index a3449c3..d3650f9 100644
--- a/jvmfwk/plugins/sunmajor/pluginlib/sunjavaplugin.cxx
+++ b/jvmfwk/plugins/sunmajor/pluginlib/sunjavaplugin.cxx
@@ -765,10 +765,10 @@ javaPluginError jfw_plugin_existJRE(const JavaInfo *pInfo, sal_Bool *exist)
    {
        ret = JFW_PLUGIN_E_ERROR;
    }
#ifdef MACOSX
    //We can have the situation that the JavaVM runtime library is not
    //contained within JAVA_HOME. Then the check for JAVA_HOME would return
    //true although the runtime library may not be loadable.
    //Or the JAVA_HOME directory of a deinstalled JRE left behind.
    if (ret == JFW_PLUGIN_E_NONE && *exist == sal_True)
    {
        OUString sRuntimeLib = getRuntimeLib(pInfo->arVendorData);
@@ -796,7 +796,6 @@ javaPluginError jfw_plugin_existJRE(const JavaInfo *pInfo, sal_Bool *exist)
                       + sRuntimeLib + " \n");
        }
    }
#endif
    return ret;
}