Include self-signed flag in certificates by checking SKID/AKID as well as
issuer and subject names. Although this is an incompatible change it should
have little impact in pratice because self-issued certificates that are not
self-signed are rarely encountered.
(Imported from upstream's c00f8d697aed17edbd002e2f6c989d8fbd7c4ecf)
Initial fork from f2d678e6e89b6508147086610e985d4e8416e867 (1.0.2 beta).
(This change contains substantial changes from the original and
effectively starts a new history.)
