Fix test_small_segments3 path measure test.

Fix test_small_segments3 path measure test.
Committed: https://code.google.com/p/skia/source/detail?r=5792

[bsalomon, 2012-10-03 19:03:53]

The test is reading beyond the pts array. It looks like this was copied from
test_small_segement2 but the increment wasn't changed.

[robertphillips, 2012-10-03 19:10:08]

LGTM