Check library: Dont abort if there are folders in the library that calibre does not have permission to access. Fixes #1884544 [Library check tries to read system files](https://bugs.launchpad.net/calibre/+bug/1884544)

Merge branch 'master' of https://github.com/cbhaley/calibre

src/calibre/library/check_library.py

@@ -108,6 +108,7 @@ class CheckLibrary(object):
 
             # Look for titles in the author directories
             found_titles = False
+            try:
                 for title_dir in os.listdir(auth_path):
                     if self.ignore_name(title_dir):
                         continue
@@ -135,6 +136,10 @@ class CheckLibrary(object):
                     # Record the book to check its formats
                     self.book_dirs.append((db_path, title_dir, id_))
                     found_titles = True
+            except:
+                traceback.print_exc()
+                # Sort-of check: exception processing directory
+                self.failed_folders.append((auth_dir, traceback.format_exc(), []))
 
             # Fourth check: author directories that contain no titles
             if not found_titles: