Fix testSyncFiles_extStorageVariable and testSyncFiles_normal

On fugu and molly and others,
 - com.android.cts.aadb.TestDeviceFuncTest#testSyncFiles_extStorageVariable
 - com.android.cts.aadb.TestDeviceFuncTest#testSyncFiles_normal
fail when timezone (persist.sys.timezone prop) is set on the
target Android device (e.g., to "Asia/Tokyo"). So fix it by
taking the timezone into account.

Bug: 19007115
Change-Id: Ib47fd27506caefda6a5f5becf9a45da9b347929e
1 file changed