EGL: Close Multifile Blobcache files after mapping am: 87ab77175b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/native/+/24882477

Change-Id: I64794d21dc6707ccdd5b4ef17825e79e5c2764b9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>