[FS#753] Alternatives support breaks 'ip' symlink when only 'tc' is installed (breaks e.g. SQM)

[LEDE Bugs]

The following task is now closed:

FS#753 - Alternatives support breaks 'ip' symlink when only 'tc' is installed (breaks e.g. SQM)
User who did this - Yousong Zhou (yousong)

Reason for closing: Fixed
More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=753