fix fuzz

if built path is empty, don't add a zero-length line
(when start and end of interval are equal)

R=kjlubick@google.com

Docs-Preview: https://skia.org/?cl=114940
Bug: skia:
Change-Id: I018eaec4d31daf3e3820641127b63d047e4ee007
Reviewed-on: https://skia-review.googlesource.com/114940
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Cary Clark <caryclark@skia.org>
1 file changed