Remove three useless tests files

The asn1test depends on asn1_mac.h which had a date with the bitbucket a
few years back (and the test "isn't meant to run particularly, it's just
to test type checking"). methtest.c tests an API that was never present
in OpenSSL's git history. r160test.c is nothing but a licence.

"nuke away" jsing

Author: tb