[automerger skipped] libprocessgroup: Use WriteStringToFd for WriteFileAction am: 1458350370 -s ours am: cff7952df2 -s ours am: 0cad4c44bc -s ours

am skip reason: Merged-In Id79f9e1095f52079393c58edb9a4d526f4cc6b5e with SHA-1 d4c53518fe is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/17061322

Change-Id: I6a33c4b70b70918580e9c1155b0aaf08fd7efb54
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>