added '-p' to `mkdir /opt`, so doesn't error if /opt exists

library/gradle

@@ -1,6 +1,6 @@
 Maintainers: Keegan Witt <[email protected]> (@keeganwitt)
 GitRepo: https://github.com/keeganwitt/docker-gradle.git
-GitCommit: ac54cbdd0f8de7545737661d595c2f2ba468620e
+GitCommit: 9a96b182fea818a493c9e2b8df46cb59af1cefd1
 
 Tags: 5.2.0-jdk8, 5.2-jdk8, jdk8, 5.2.0-jdk, 5.2-jdk, jdk, 5.2.0, 5.2, latest
 Architectures: amd64, arm32v5, arm32v7, arm64v8, i386, ppc64le, s390x