Fix segmentation violation when ASN1_TYPE_cmp is passed a boolean type. This
can be triggered during certificate verification so could be a DoS attack
against a client or a server enabling client authentication.

CVE-2015-0286

(Imported from upstream's e677e8d13595f7b3287f8feef7676feb301b0e8a.)

Change-Id: I5faefc190568504bb5895ed9816a6d80432cfa45
Reviewed-on: https://boringssl-review.googlesource.com/4048
Reviewed-by: Adam Langley <agl@google.com>