[runtime] Fix a regression caused by a0afa38296b8a3b0382bf34ce777357d2553c0f0.
[System] Fixed an error in the implementation of System.Net.IPAddress.IsIPv6Teredo

The property was introduced with PR #870 but it missed to convert network byte order to host byte order, so the comparison
wasn't working correctly and the corresponding unit test failed. @marek-safar erroneously "fixed" the test in 27e07c7.

This is the corrected implementation and the original test now works as intended.
Merge pull request #894 from antoniusriha/fixIsIPv6Teredo

[System] Fixed an error in the implementation of System.Net.IPAddress.IsIPv6Teredo
Merge pull request #893 from antoniusriha/fixregression

[runtime] Fix a regression caused by a0afa38296b8a3b0382bf34ce777357d2553c0f0
Fix 'make dist' broken since 35287878

In commit 35287878b9785efeaeb854afb6ee4509f5714d65:

    [xbuild] Reorganize xbuild targets/frameworks/bin data

Several files were shuffled around, but the EXTRA_DISTFILES was
not fully updated with the new file paths.

This patch is required to build a 3.2.7 tarball.
[xbuild] Define VisualStudioVersion, since F# projects can depend on it
[xbuild] Fix PCL 4.5 targets