deps,tools: include SipHash in LICENSE

LICENSE

@@ -774,6 +774,17 @@ The externally maintained libraries used by Node.js are:
     OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   """
 
+- SipHash, located at deps/v8/src/third_party/siphash, is licensed as follows:
+  """
+    SipHash reference C implementation
+
+    Copyright (c) 2016 Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
+
+    To the extent possible under law, the author(s) have dedicated all
+    copyright and related and neighboring rights to this software to the public
+    domain worldwide. This software is distributed without any warranty.
+  """
+
 - zlib, located at deps/zlib, is licensed as follows:
   """
     zlib.h -- interface of the 'zlib' general purpose compression library

tools/license-builder.sh

@@ -64,6 +64,8 @@ addlicense "OpenSSL" "deps/openssl" \
 addlicense "Punycode.js" "lib/punycode.js" \
            "$(curl -sL https://raw.githubusercontent.com/bestiejs/punycode.js/master/LICENSE-MIT.txt)"
 addlicense "V8" "deps/v8" "$(cat ${rootdir}/deps/v8/LICENSE)"
+addlicense "SipHash" "deps/v8/src/third_party/siphash" \
+           "$(sed -e '/You should have received a copy of the CC0/,$d' -e 's/^\/\* *//' -e 's/^ \* *//' deps/v8/src/third_party/siphash/halfsiphash.cc)"
 addlicense "zlib" "deps/zlib" \
            "$(sed -e '/The data format used by the zlib library/,$d' -e 's/^\/\* *//' -e 's/^ *//' ${rootdir}/deps/zlib/zlib.h)"