This gets a PEM file with (possibly) many X509 certificates among others and
    constructs an array containing each X509 certificate as a separate PEM
    string. This can serve for splitting a PEM file containing multiple
    certificates (for example CA file) to single certificate entries so it can
    be examined with get_certificate_info function.  Note that the array can
    contain NULL elements in places where in the PEM file there are blocks other
    than X509 PEM certificates.