clamp fixed divide to 32 bits
clamp fixed divide to 32 bits

In SkEdge::setLine, the numerator is a 26.6 fixed number.
SkFixedDiv shifts it up by an additional 16 bits. If the
y interval is small, the result overflows 32 bits.

The code pins in 64 bit space before down-casting the result.

R=reed@google.com
BUG=skia:4708
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1583453002

Review URL: https://codereview.chromium.org/1583453002

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