Fix idmap leak in zygote process

Fix a idmap leak in AssetManager::addSystemOverlays.
And, The fix could also prevent fd leak of idmap.

Test: none
Bug: 32691930

Signed-off-by: Hyangseok Chae <neo.chae@lge.com>

(cherry picked from commit 6a742a38509693f8b39ee9a5ad2803fca12688bf)

Change-Id: Idc4af77db2b0cb739bd6b009b6af0f9123be1aac
(cherry picked from commit 0244ca8d10dfc27e14f481fe649b89f7638c48eb)
1 file changed