bn_exp.c: move check for AD*X to rsaz-avx2.pl.

This ensures high performance is situations when assembler supports
AVX2, but not AD*X.
Remove ancient obsolete files under pkcs7.
Make sure BN_sqr can never return a negative value.

PR#3410
Memory leak and NULL dereference fixes.

PR#3403
Fix OID encoding for one component.

OIDs with one component don't have an encoding.

PR#2556 (Bug#1)
Rebuild OID table.
Clarify docs.

Document that the certificate passed to SSL_CTX_add_extra_chain_cert()
should not be freed by the application.

PR#3409
Don't advertise ECC ciphersuits in SSLv2 compatible client hello.

PR#3374
Handle IPv6 addresses in OCSP_parse_url.

PR#2783
Add SHA256 Camellia ciphersuites from RFC5932

PR#2800
Tolerate critical AKID in CRLs.

PR#3014
RT 487.  Mention that generated primes are "at least" B<bits> long.
bn/asm/rsaz-avx2.pl: fix occasional failures.
Fix for EVP_PBE_alg_add().

In EVP_PBE_alg_add don't use the underlying NID for the cipher
as it may have a non-standard key size.

PR#3206
Remove redundant check.

PR#3174
Fix typo in ideatest.c
Fix compilation with -DSSL_DEBUG -DTLS_DEBUG -DKSSL_DEBUG

PR#3141
Don't disable state strings with no-ssl2

Some state strings were erronously not compiled when no-ssl2
was set.

PR#3295
Typo.

PR#3107
x86_64 assembly pack: refine clang detection.