Roll external/skia 37bbfe3ea..45a6f147b (5 commits)

https://skia.googlesource.com/skia.git/+log/37bbfe3ea..45a6f147b

2017-09-29 robertphillips@google.com Clear uniquely keyed texture proxies out of ResourceCache when it is deleted
2017-09-29 liyuqian@google.com Add width and height option to SampleApp
2017-09-29 benjaminwagner@google.com Add AVX512 jobs.
2017-09-29 egdaniel@google.com Revert "Revert "Update GrBitmapTextureMaker for handling mipped requests""
2017-09-29 benjaminwagner@google.com Remove duplicate config for MacMini.

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Change-Id: I2258e635f9561d66176c162385614092af7e6cb4
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