Fix incorrect bounds check in amd64 assembly version of bn_mul_mont();
noticed and fix by Fedor Indutny of Joyent
( https://github.com/joyent/node/issues/7704 )
Remove OPENSSL_instrument_halt and OPENSSL_far_spin, which both might
have been used under DJGPP in the previous century (if at all).
wrap getenv OPENSSL_ALLOW_PROXY_CERTS in an issetugid check, to protect
setuid applications from being fooled.
ok miod
Remove the OPENSSL_*cap getenv's.  A program should not be able to
change the behaviour of the library in such a complicated fashion.
ok miod