import farmhash

Summary:
This diff imports farmhash.h and farmhash.cc from
https://github.com/google/farmhash and updates the public_tld license
file accordingly. Build integration and namespace changes will occur in
later diffs.

Reviewed By: yfeldblum

Differential Revision: D13436553

fbshipit-source-id: 7a081032cb35a1a3e1cd14e2edf2685906956396

LICENSE

@@ -175,3 +175,26 @@
       of your accepting any such warranty or additional liability.
 
    END OF TERMS AND CONDITIONS
+
+
+Files in folly/external/farmhash licensed as follows
+
+    Copyright (c) 2014 Google, Inc.
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.