Support OpenSSL 1.1.0.

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>

configure

@@ -9538,9 +9538,9 @@ else
   as_fn_error $? "library 'crypto' is required for OpenSSL" "$LINENO" 5
 fi
 
-     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for SSL_library_init in -lssl" >&5
-$as_echo_n "checking for SSL_library_init in -lssl... " >&6; }
-if ${ac_cv_lib_ssl_SSL_library_init+:} false; then :
+     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for SSL_new in -lssl" >&5
+$as_echo_n "checking for SSL_new in -lssl... " >&6; }
+if ${ac_cv_lib_ssl_SSL_new+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
@@ -9554,27 +9554,27 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char SSL_library_init ();
+char SSL_new ();
 int
 main ()
 {
-return SSL_library_init ();
+return SSL_new ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_ssl_SSL_library_init=yes
+  ac_cv_lib_ssl_SSL_new=yes
 else
-  ac_cv_lib_ssl_SSL_library_init=no
+  ac_cv_lib_ssl_SSL_new=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_ssl_SSL_library_init" >&5
-$as_echo "$ac_cv_lib_ssl_SSL_library_init" >&6; }
-if test "x$ac_cv_lib_ssl_SSL_library_init" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_ssl_SSL_new" >&5
+$as_echo "$ac_cv_lib_ssl_SSL_new" >&6; }
+if test "x$ac_cv_lib_ssl_SSL_new" = xyes; then :
   cat >>confdefs.h <<_ACEOF
 #define HAVE_LIBSSL 1
 _ACEOF
@@ -9644,9 +9644,9 @@ else
   as_fn_error $? "library 'eay32' or 'crypto' is required for OpenSSL" "$LINENO" 5
 fi
 
-     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing SSL_library_init" >&5
-$as_echo_n "checking for library containing SSL_library_init... " >&6; }
-if ${ac_cv_search_SSL_library_init+:} false; then :
+     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing SSL_new" >&5
+$as_echo_n "checking for library containing SSL_new... " >&6; }
+if ${ac_cv_search_SSL_new+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_func_search_save_LIBS=$LIBS
@@ -9659,11 +9659,11 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char SSL_library_init ();
+char SSL_new ();
 int
 main ()
 {
-return SSL_library_init ();
+return SSL_new ();
   ;
   return 0;
 }
@@ -9676,25 +9676,25 @@ for ac_lib in '' ssleay32 ssl; do
     LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
   fi
   if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_search_SSL_library_init=$ac_res
+  ac_cv_search_SSL_new=$ac_res
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext
-  if ${ac_cv_search_SSL_library_init+:} false; then :
+  if ${ac_cv_search_SSL_new+:} false; then :
   break
 fi
 done
-if ${ac_cv_search_SSL_library_init+:} false; then :
+if ${ac_cv_search_SSL_new+:} false; then :
 
 else
-  ac_cv_search_SSL_library_init=no
+  ac_cv_search_SSL_new=no
 fi
 rm conftest.$ac_ext
 LIBS=$ac_func_search_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_SSL_library_init" >&5
-$as_echo "$ac_cv_search_SSL_library_init" >&6; }
-ac_res=$ac_cv_search_SSL_library_init
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_SSL_new" >&5
+$as_echo "$ac_cv_search_SSL_new" >&6; }
+ac_res=$ac_cv_search_SSL_new
 if test "$ac_res" != no; then :
   test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"