fdd241a1e0
By declaring a <restrict-update> tag in its manifest, a system package can restrict its update to be the singular package that has the same given hash. An update's hash is the SHA-512 across all its APKs [i.e. for splits, the SHA-512 is calculated over the concatenation of the base plus all splits]. The restriction only applies to system packages. Bug: 28398205 Change-Id: Iec493fc8ef27edee53f1d437cb0caaa78782f329