Add basic Xamarin.Mac support

Summary:
- Does not contain "magic" found in YogaKit yet, but enough to get started
- Simple test project showing use
- YGInteropSetLogger and YGNodeInit(IntPtr) were missing from native lib built by buck
Closes https://github.com/facebook/yoga/pull/278

Reviewed By: emilsjolander

Differential Revision: D4388480

Pulled By: splhack

fbshipit-source-id: a7387bb5b5554b6fce80d08c23e4fa18a4611cce

csharp/Mac/Facebook.Yoga.Mac.sln

@@ -0,0 +1,25 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 2012
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Facebook.Yoga.Mac.Test", "Facebook.Yoga.Mac.Test\Facebook.Yoga.Mac.Test.csproj", "{64E0AB97-A904-4607-A535-EEA5A966C09E}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Facebook.Yoga.Mac", "Facebook.Yoga.Mac.csproj", "{19A1C7D7-C9CC-476A-B604-DF6A3DE1BA71}"
+EndProject
+Project("{D954291E-2A0B-460D-934E-DC6B0785DB48}") = "Facebook.Yoga.Shared", "..\Facebook.Yoga\Facebook.Yoga.Shared.shproj", "{91C42D32-291D-4B72-90B4-551663D60B8B}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{64E0AB97-A904-4607-A535-EEA5A966C09E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{64E0AB97-A904-4607-A535-EEA5A966C09E}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{64E0AB97-A904-4607-A535-EEA5A966C09E}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{64E0AB97-A904-4607-A535-EEA5A966C09E}.Release|Any CPU.Build.0 = Release|Any CPU
+		{19A1C7D7-C9CC-476A-B604-DF6A3DE1BA71}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{19A1C7D7-C9CC-476A-B604-DF6A3DE1BA71}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{19A1C7D7-C9CC-476A-B604-DF6A3DE1BA71}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{19A1C7D7-C9CC-476A-B604-DF6A3DE1BA71}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal