Merge "fastboot device: Disallow implicit conversion from unique_fd to int."...

Merge "fastboot device: Disallow implicit conversion from unique_fd to int." am: 2af05048 am: b72da0a2

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1649753

Change-Id: Ie5352c29ffcba147c73f8d119b2775623e3c8871