sync after Zcash macOS patches are in

zcash/Makefile

@@ -3,7 +3,7 @@ target_name ?= zcash
 
 include ../Makefile.build
 
-ZCASH_VERSION=v1.0.15
+ZCASH_VERSION=master
 
 zcash_clone:
 	if [ ! -d "zcash_$(ZCASH_VERSION)" ]; then git clone -b $(ZCASH_VERSION) https://github.com/zcash/zcash.git zcash_$(ZCASH_VERSION); fi

zcash/patches/006-zcash-macos-fetch.patch

@@ -1,14 +1,5 @@
-From 4c2120c7365ae1099459bb75739b226f9271e6f7 Mon Sep 17 00:00:00 2001
-From: kozyilmaz <[email protected]>
-Date: Sun, 17 Dec 2017 20:18:03 +0300
-Subject: [PATCH] [macOS] use shlock instead of flock in fetch-params
-
----
- zcutil/fetch-params.sh | 26 +++++++++++++++++++-------
- 1 file changed, 19 insertions(+), 7 deletions(-)
-
 diff --git a/zcutil/fetch-params.sh b/zcutil/fetch-params.sh
-index b8511c7802..9eb52bec1d 100755
+index 10bade7c..ec37e1e7 100755
 --- a/zcutil/fetch-params.sh
 +++ b/zcutil/fetch-params.sh
 @@ -2,7 +2,11 @@
@@ -24,7 +15,7 @@ index b8511c7802..9eb52bec1d 100755
 
  SPROUT_PKEY_NAME='sprout-proving.key'
  SPROUT_VKEY_NAME='sprout-verifying.key'
-@@ -125,12 +129,20 @@ EOF
+@@ -102,12 +106,20 @@ EOF
  # Use flock to prevent parallel execution.
  function lock() {
      local lockfile=/tmp/fetch_params.lock