[Fix #531] Don't match strings when using clojure-rename-ns-alias.

[anthonygalea]

Is it acceptable to use font locking to determine whether a string was matched?

• The commits are consistent with our [contribution guidelines][1].
• You've added tests (if possible) to cover your change(s). Bugfix, indentation, and font-lock tests are extremely important!
• You've run M-x checkdoc and fixed any warnings in the code you've written.
• You've updated the changelog (if adding/changing user-visible functionality).
• You've updated the readme (if adding/changing user-visible functionality).

[bbatsov]

Is it acceptable to use font locking to determine whether a string was matched?

Generally it's better to use syntax-ppss (https://www.gnu.org/software/emacs/manual/html_node/elisp/Position-Parse.html)

[anthonygalea]

thanks @bbatsov

[bbatsov]

Thank you!