Userland: ls division by zero.

When the terminal app window became smaller than the longest filename,
a division by zero occured while calculating the offset.

Userland/ls.cpp

@@ -272,7 +272,9 @@ int do_file_system_object_short(const char* path)
 
  if (!print_filesystem_object_short(pathbuf, name.characters(), &nprinted))
  return 2;
- int offset = columns % longest_name / (columns / longest_name);
+ int offset = 0;
+ if (columns > longest_name)
+ offset = columns % longest_name / (columns / longest_name);
  /* The offset must be at least 2 because:
  * - With each file an aditional char is printed e.g. '@','*'.
  * - Each filename must be separated by a space.