Correct whirlpool test

It depended on 'openssl no-wp', which always exited with code 0, so
this test would never be performed, and this, I never discovered that
the program it's supposed to run was misspellt.  Furthermore, the
feature to check is 'whirlpool', not 'wp'.

All corrected.

Reviewed-by: Stephen Henson <steve@openssl.org>