Add four new Linux RIDs.

* Linux Mint 18: Binary compatible with Ubuntu 16.04

The following RIDs will need additional work to enable platform-specific
packages to be produced for them:

* Ubuntu 16.10
* Fedora 24
* openSUSE 42.1


Commit migrated from https://github.com/dotnet/corefx/commit/cb217c066c93e331059f0273f816074faf3f456c

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

@@ -310,7 +310,14 @@
         "ubuntu.16.04-x64": {
             "#import": [ "ubuntu.16.04", "ubuntu-x64" ]
         },
-        
+
+        "ubuntu.16.10": {
+            "#import": [ "ubuntu" ]
+        },
+        "ubuntu.16.10-x64": {
+            "#import": [ "ubuntu.16.10", "ubuntu-x64" ]
+        },
+
         "linuxmint.17": {
             "#import": [ "ubuntu.14.04" ]
         },
@@ -339,6 +346,13 @@
             "#import": [ "linuxmint.17.3", "linuxmint.17.2-x64" ]
         },
 
+        "linuxmint.18": {
+            "#import": [ "ubuntu.16.04" ]
+        },
+        "linuxmint.18-x64": {
+            "#import": [ "linuxmint.18", "ubuntu.16.04-x64" ]
+        },
+
         "fedora": {
             "#import": [ "linux" ]
         },
@@ -353,6 +367,13 @@
             "#import": [ "fedora.23", "fedora-x64" ]
         },
 
+        "fedora.24": {
+            "#import": [ "fedora" ]
+        },
+        "fedora.24-x64": {
+            "#import": [ "fedora.24", "fedora-x64" ]
+        },
+
         "opensuse": {
             "#import": [ "linux" ]
         },
@@ -365,6 +386,13 @@
         },
         "opensuse.13.2-x64": {
             "#import": [ "opensuse.13.2", "opensuse-x64" ]
+        },
+
+        "opensuse.42.1": {
+            "#import": [ "opensuse" ]
+        },
+        "opensuse.42.1-x64": {
+            "#import": [ "opensuse.42.1", "opensuse-x64" ]
         }
     }
  }