title: Prevent JGit from reading the native git config
body: <p>I am using JGit in an app. This app has a <code>SecurityManager</code> in place that allows only specific white-listed classes and methods from spawning new processes.</p>
  
  <p>JGit internally is discovering if a native git is installed and tries to read its config in <code>org.eclipse.jgit.util.FS.discoverGitSystemConfig()</code> and even tries to find hooks in <code>org.eclipse.jgit.util.FS_POSIX.findHook()</code> and see if they are executable. </p>
  
  <p>Because of the aforementioned Security Manager in place, JGit cannot function and fails.
  I tried to find in the documentation if there is a way to suppress this behavior?</p>