add freebsd-x64 toolset

Author: alexrp

src/freebsd-x64/build/Vezel.Zig.Toolsets.freebsd-x64.props

@@ -0,0 +1,8 @@
+<Project>
+    <PropertyGroup>
+        <ZigToolsetPath>$([MSBuild]::NormalizeDirectory('$(MSBuildThisFileDirectory)../tools'))</ZigToolsetPath>
+        <ZigExePath>$([MSBuild]::NormalizePath('$(ZigToolsetPath)zig'))</ZigExePath>
+        <ZigLibPath>$([MSBuild]::NormalizeDirectory('$(ZigToolsetPath)lib'))</ZigLibPath>
+        <ZigDocPath>$([MSBuild]::NormalizeDirectory('$(ZigToolsetPath)doc'))</ZigDocPath>
+    </PropertyGroup>
+</Project>

src/freebsd-x64/build/Vezel.Zig.Toolsets.freebsd-x64.targets

@@ -0,0 +1 @@
+<Project />

src/freebsd-x64/freebsd-x64.proj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.Build.NoTargets">
+    <PropertyGroup>
+        <ZigBuildRuntime>freebsd-x64</ZigBuildRuntime>
+        <ZigArchiveName>x86_64-freebsd</ZigArchiveName>
+        <ZigArchiveType>tar.xz</ZigArchiveType>
+    </PropertyGroup>
+</Project>