Changes needed to build at all:

- Check for SSL_new in configure, now that SSL_library_init is a macro.
- Do not access struct members directly. This includes some new code in
  pgcrypto, to use the resource owner mechanism to ensure that we don't
  leak OpenSSL handles, now that we can't embed them in other structs
  anymore.
- RAND_SSLeay() -> RAND_OpenSSL()

Changes that were needed to silence deprecation warnings, but were not
strictly necessary:

- RAND_pseudo_bytes() -> RAND_bytes().
- SSL_library_init() and OpenSSL_config() -> OPENSSL_init_ssl()
- ASN1_STRING_data() -> ASN1_STRING_get0_data()
- DH_generate_parameters() -> DH_generate_parameters()
- Locking callbacks are not needed with OpenSSL 1.1.0 anymore. (Good
  riddance!)

Also change references to SSLEAY_VERSION_NUMBER with OPENSSL_VERSION_NUMBER,
for the sake of consistency. OPENSSL_VERSION_NUMBER has existed since time
immemorial.

Fix SSL test suite to work with OpenSSL 1.1.0. CA certificates must have
the "CA:true" basic constraint extension now, or OpenSSL will refuse them.
Regenerate the test certificates with that. The "openssl" binary, used to
generate the certificates, is also now more picky, and throws an error
if an X509 extension is specified in "req_extensions", but that section
is empty.

Backpatch to all supported branches, per popular demand. In back-branches,
we still support OpenSSL 0.9.7 and above. OpenSSL 0.9.6 should still work
too, but I didn't test it. In master, we only support 0.9.8 and above.

Patch by Andreas Karlsson, with additional changes by me.

Discussion: <20160627151604.GD1051@msg.df7cb.de>

pgcrypto already supports key-stretching during symmetric encryption,
including the salted-and-iterated method; but the number of iterations
was not configurable.  This commit implements a new s2k-count parameter
to pgp_sym_encrypt() which permits selecting a larger number of
iterations.

Author: Jeff Janes

This includes removing tabs after periods in C comments, which was
applied to back branches, so this change should not effect backpatching.

Specifically, on-stack memset() might be removed, so:

	* Replace memset() with px_memset()
	* Add px_memset to copy_crlf()
	* Add px_memset to pgp-s2k.c

Patch by Marko Kreen

Report by PVS-Studio

Backpatch through 8.4.

pgp.h used to require including mbuf.h and px.h first.  Include those in
pgp.h, so that it can be used without prerequisites.  Remove mbuf.h
inclusions in .c files where mbuf.h features are not used
directly.  (px.h was always used.)

This warning is new in gcc 4.6 and part of -Wall.  This patch cleans
up most of the noise, but there are some still warnings that are
trickier to remove.

provided by Andrew.

be more wary about having a value for BYTE_ORDER, clean up randomly-
chosen ways of including Postgres core headers.
Marko Kreen and Tom Lane