Use nextafter rather than std::nextafter, it's more widely available

Bug: skia:
Change-Id: Idffe99cde348af83ae4290614c44767fffe36609
Reviewed-on: https://skia-review.googlesource.com/19120
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
1 file changed