build: update siphash lib to latest version w/ ARM fix

In this commit, we update the siphash lib we use to the latest version
as it was discovered that the assembly for certain ARM machines has a
flaw which causes it to compute an _incorrect_ siphash function. The
upstream lib has since disabled the assembly after this was discovered.
We update as well in order to ensure that ARM machines will produce the
proper GCS filters.

glide.lock

@@ -1,8 +1,8 @@
-hash: 30562f0035d9bb4d4ee531762e4f7f762ede916255e9aa781df58537651f7382
-updated: 2018-07-06T16:07:52.877260592-07:00
+hash: e6f57b384b22282a2cb4e96aea9c46dc455b44336da09e64a9b19d13d877e7a4
+updated: 2018-08-22T19:51:39.57143044-07:00
 imports:
 - name: github.com/aead/siphash
-  version: e404fcfc888570cadd1610538e2dbc89f66af814
+  version: 83563a290f60225eb120d724600b9690c3fb536f
 - name: github.com/btcsuite/btclog
   version: 84c8d2346e9fc8c7b947e243b9c24e6df9fd206a
 - name: github.com/btcsuite/btcutil

glide.yaml

@@ -33,3 +33,5 @@ import:
 - package: github.com/jessevdk/go-flags
   version: 1679536dcc895411a9f5848d9a0250be7856448c
 - package: github.com/jrick/logrotate
+- package: github.com/aead/siphash
+  version: 83563a290f60225eb120d724600b9690c3fb536f