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 6a742a3850)

Change-Id: Idc4af77db2b0cb739bd6b009b6af0f9123be1aac

libs/androidfw/AssetManager.cpp

@@ -798,6 +798,7 @@ void AssetManager::addSystemOverlays(const char* pathOverlaysList,
             sharedRes->add(oass, oidmap, offset + 1, false);
             const_cast<AssetManager*>(this)->mAssetPaths.add(oap);
             const_cast<AssetManager*>(this)->mZipSet.addOverlay(targetPackagePath, oap);
+            delete oidmap;
         }
     }
     fclose(fin);