Add back FeeBSD 12 and 13, they are still supported.

Author: tmds

src/libraries/Microsoft.NETCore.Platforms/src/runtime.compatibility.json

@@ -2712,6 +2712,65 @@
     "any",
     "base"
   ],
+  "freebsd.12": [
+    "freebsd.12",
+    "freebsd",
+    "unix",
+    "any",
+    "base"
+  ],
+  "freebsd.12-arm64": [
+    "freebsd.12-arm64",
+    "freebsd.12",
+    "freebsd-arm64",
+    "freebsd",
+    "unix-arm64",
+    "unix",
+    "any",
+    "base"
+  ],
+  "freebsd.12-x64": [
+    "freebsd.12-x64",
+    "freebsd.12",
+    "freebsd-x64",
+    "freebsd",
+    "unix-x64",
+    "unix",
+    "any",
+    "base"
+  ],
+  "freebsd.13": [
+    "freebsd.13",
+    "freebsd.12",
+    "freebsd",
+    "unix",
+    "any",
+    "base"
+  ],
+  "freebsd.13-arm64": [
+    "freebsd.13-arm64",
+    "freebsd.13",
+    "freebsd.12-arm64",
+    "freebsd.12",
+    "freebsd-arm64",
+    "freebsd",
+    "unix-arm64",
+    "unix",
+    "any",
+    "base"
+  ],
+  "freebsd.13-x64": [
+    "freebsd.13-x64",
+    "freebsd.13",
+    "freebsd.12-x64",
+    "freebsd.12",
+    "freebsd-x64",
+    "freebsd",
+    "unix-x64",
+    "unix",
+    "any",
+    "base"
+  ],
   "gentoo": [
     "gentoo",
     "linux",

src/libraries/Microsoft.NETCore.Platforms/src/runtime.json

@@ -987,6 +987,40 @@
         "unix-x64"
       ]
     },
+    "freebsd.12": {
+      "#import": [
+        "freebsd"
+      ]
+    },
+    "freebsd.12-arm64": {
+      "#import": [
+        "freebsd.12",
+        "freebsd-arm64"
+      ]
+    },
+    "freebsd.12-x64": {
+      "#import": [
+        "freebsd.12",
+        "freebsd-x64"
+      ]
+    },
+    "freebsd.13": {
+      "#import": [
+        "freebsd.12"
+      ]
+    },
+    "freebsd.13-arm64": {
+      "#import": [
+        "freebsd.13",
+        "freebsd.12-arm64"
+      ]
+    },
+    "freebsd.13-x64": {
+      "#import": [
+        "freebsd.13",
+        "freebsd.12-x64"
+      ]
+    },
     "gentoo": {
       "#import": [
         "linux"

src/libraries/Microsoft.NETCore.Platforms/src/runtimeGroups.props

@@ -184,6 +184,7 @@
     <RuntimeGroup Include="freebsd">
       <Parent>unix</Parent>
       <Architectures>x64;arm64</Architectures>
+      <Versions>12;13</Versions>
     </RuntimeGroup>
 
     <RuntimeGroup Include="solaris">