build: update glide to point to latest btcutil

In this commit, we update the glide.lock file to be pinned against the
latest btcutil commit hash. btcutil has recently been updated to pull in
all changes from roasbeef's fork. Notably, it now includes the code
necessary for creating GCS filters (BIP 158).

glide.lock

@@ -1,12 +1,13 @@
 hash: 976decfaf173d97d2e4572399490637aa12e217312a7d8b28813780a738e1151
-updated: 2017-08-24T17:28:45.8117156-05:00
+updated: 2018-05-15T19:16:29.311905983-07:00
 imports:
 - name: github.com/btcsuite/btclog
   version: 84c8d2346e9fc8c7b947e243b9c24e6df9fd206a
 - name: github.com/btcsuite/btcutil
-  version: 501929d3d046174c3d39f0ea54ece471aa17238c
+  version: b9afb0b9868a757e8fcc3c3adf5b129979f9b3e6
   subpackages:
   - base58
+  - bech32
   - bloom
   - hdkeychain
 - name: github.com/btcsuite/go-socks
@@ -41,7 +42,7 @@ imports:
   - svc
   - winapi
 - name: github.com/davecgh/go-spew
-  version: 346938d642f2ec3594ed81d874461961cd0faa76
+  version: 8991bc29aa16c548c550c7ff78260e27b9ab7c73
   subpackages:
   - spew
 - name: github.com/jessevdk/go-flags
@@ -51,7 +52,7 @@ imports:
   subpackages:
   - rotator
 - name: golang.org/x/crypto
-  version: 122d919ec1efcfb58483215da23f815853e24b81
+  version: 1a580b3eff7814fc9b40602fd35256c63b50f491
   subpackages:
   - ripemd160
 testImports: []