[Mac] Update numerous availability tags from 10.12.1 to 10.12.2

[timrisi]

From a 10.12.2 beta diff that was never implemented.

We're waiting to merge after the xcode8.3 branch has been merged back into master to try to avoid making that merge any harder than it has to be.

[monojenkins]

Build failure

[spouliot]

This can now be merged (without causing conflicts with xcode8.3)

[timrisi]

Build

[monojenkins]

Build success

[monojenkins]

Build failure

[timrisi]

Build

[monojenkins]

Build failure

[timrisi]

Build

[monojenkins]

Build failure

[timrisi]

Build

[monojenkins]

Build failure

[spouliot]

@timrisi the build fails with

17:19:42 /Users/builder/jenkins/workspace/xamarin-macios-pr-builder/src/appkit.cs(13683,0): error CS1028: Unexpected processor directive (no #if for this #else)
17:19:42 /Users/builder/jenkins/workspace/xamarin-macios-pr-builder/src/appkit.cs(13685,0): error CS1028: Unexpected processor directive (no #if for this #endif)
17:19:43 /Users/builder/jenkins/workspace/xamarin-macios-pr-builder/src/appkit.cs(13683,0): error CS1028: Unexpected processor directive (no #if for this #else)
17:19:43 /Users/builder/jenkins/workspace/xamarin-macios-pr-builder/src/appkit.cs(13685,0): error CS1028: Unexpected processor directive (no #if for this #endif)

Please always review logs on failures (before asking bots to build again) and file bugs (or fix) as appropriate.

[timrisi]

Yah I saw that in the last build. There were several that failed with git issues before hand.

[monojenkins]

Build success