Attempt to fix memory corruption

Author: jairbubbles

LibGit2Sharp/Core/NativeMethods.cs

@@ -757,7 +757,7 @@ internal static extern int git_libgit2_opts(int option,
 
         // git_libgit2_opts(GIT_OPT_SET_EXTENSIONS, const char **extensions, size_t len)
         [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
-        internal static extern int git_libgit2_opts(int option, GitStrArray extensions);
+        internal static extern int git_libgit2_opts(int option, IntPtr extensions, UIntPtr len);
 
         // git_libgit2_opts(GIT_OPT_GET_EXTENSIONS, git_strarray *out)
         [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]

LibGit2Sharp/Core/Proxy.cs

@@ -3505,7 +3505,7 @@ public static void git_libgit2_opts_set_extensions(string[] extensions)
         {
             using(var array = GitStrArrayManaged.BuildFrom(extensions))
             {
-                var res = NativeMethods.git_libgit2_opts((int)LibGit2Option.SetExtensions, array.Array);
+                var res = NativeMethods.git_libgit2_opts((int)LibGit2Option.SetExtensions, array.Array.Strings, array.Array.Count);
                 Ensure.ZeroResult(res);
             }
         }