Merge branch 'hb/gitweb-project-list' into maint

When a directory is not readable, "gitweb" fails to build the
project list.  Work this around by skipping such a directory.

It might end up hiding a problem under the rug and a better
solution might be to loudly complain to the administrator pointing
out the problematic directory, but this will at least make it
"work".

* hb/gitweb-project-list:
  gitweb: skip unreadable subdirectories

diff --cc gitweb/gitweb.perl
Simple merge