count is an int, so constrain it to a 32-bit w-register.
count is an int, so constrain it to a 32-bit w-register.

This piece of code is already 64-bit only, so we don't need to think about ARMv7.

Hopefully this shuts up the warnings.  They were harmless.

If this doesn't work (it's relatively new modifier, so maybe some compilers barf), an alternative is to cast count to a size_t.

BUG=skia:4686
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1527123003
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review URL: https://codereview.chromium.org/1527123003

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