CVE-2020-10704: lib util asn1: Add ASN.1 max tree depth

CVE-2020-10704: lib util asn1: Add ASN.1 max tree depth

Add maximum parse tree depth to the call to asn1_init, which will be
used to limit the depth of the ASN.1 parse tree.

Credit to OSS-Fuzz

REF: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=20454
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14334

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>