bump grootfs
bump grootfs

[finishes #159297203]

Submodule src/code.cloudfoundry.org/grootfs 1c1c216..ccf4c36:
  > Improved Removeall function for long path names

Co-authored-by: Oliver Stenbom <887431a72390788bfd0b2c985b8a03965a0d621a@pivotal.io>

cloudfoundry-incubator/guardian-release,cloudfoundry-incubator/guardian-release,cloudfoundry-incubator/guardian-release