Keystore 2.0 engine: Handle legacy PEM certificates.

Keystore 2.0 in Android S requires all new certificates to be stored in
DER format, however, when upgrading from R or older, there may be
certificates stored in PEM format. This patch allows keystore2-engine to
extract the public keys from certificates in either format.

Bug: 199155260
Test: N/A
Change-Id: I4bd5befcef15af5fbc2cbec3fdf4d581b1558b56
1 file changed