runtimes/charliecloud: fix patch fuzz
---- a/test/chtest/Build 2018-07-12 09:44:05.000000000 -0700
-+++ b/test/chtest/Build 2018-07-20 10:20:14.000000000 -0700
+--- a/test/chtest/Build 2018-09-04 12:15:54.000000000 -0700
++++ b/test/chtest/Build 2018-10-24 08:51:20.000000000 -0700
set -ex
-WORKDIR=$3
+WORKDIR=$4
MIRROR=http://dl-cdn.alpinelinux.org/alpine/v3.6
- APK_TOOLS=apk-tools-static-2.7.6-r0.apk
+ APK_TOOLS=apk-tools-static-2.7.5-r0.apk
IMG="$WORKDIR/img"
## Bootstrap base Alpine Linux.
