std.file.setTimes: on macOS use setattrlist to avoid truncating timestamp precision to microseconds

[n8sh]

This was brought to my attention by a unit test in CyberShadow/ae that was failing on macOS because it was storing a result of timeLastModified then using the stored value as an argument to setTimes and expecting that the next call to timeLastModified would yield the same result as the stored value. The problem is that core.sys.posix.sys.stat does not have utimensat for macOS, which is because it only became available in macOS starting from version 10.13 which was released in 2017. As an alternative setattrlist can be used with any version of macOS to set timestamps with the same precision as utimensat.

[dlang-bot]

Thanks for your pull request, @n8sh!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	20785	normal	std.file.setTimes: on macOS use setattrlist to avoid truncating timestamp precision to microseconds

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "stable + phobos#7466"

[CyberShadow]

Thank you!

What do you think about adding the extern(C) declarations to Druntime first, then using them here?

[n8sh]

Created dlang/druntime#3076. Let's see where it goes.

[n8sh]

Changed this PR to target stable. Please consider moving forward with this bug fix without waiting for dlang/druntime#3076. If/when that PR is accepted the code here can be updated to use it.