fix infinite loop crash - issue #495

[perfectionaq]

Summary

Fix an infinite loop caused by calling skeletonLayoutSubviews within itself. This sometimes can cause an infinite loop and a crash.

issue 495

Requirements (place an x in each of the [ ])

• [x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.